I was going to mention my mother’s perushke, but then this thread started sounding familiar, and voila
I struggled with chile rellanos until I finaly submitted to following directions and finding a recipe that agreed with me.
I made cashew chicken once. I felt like I was doing chemistry but it turned out pretty darn good. Problem is it’s expensive to make if I only do it once in a while.
One thing I can never get right is green Chile sauce. I’ve tried several recipes to get something like the stuff I can get in any average New Mexico eatery, but I can’t get there. By a long shot.
I made Veal Oscar and, for some idiotic reason, chose to whisk the bearnaise by hand.
This was probably the most difficult dish I’ve done.
For pure time-consumingness, I’ll go with empanadas.
I think the most time consuming single dish I’ve made was Mutant Chicken. The fact that I had no recipe (was winging it) probably slowed things more than a bit. It also makes it impossible to give anyone a recipe. The best I can do is an overall description.
Bone two chickens, leaving the skin intact and the leg and wing bones in place. One of these will turn out better than the other. Marinade it in wine and spices*. A ziploc bag works well for that.
Marinade some chicken livers in the same marinade.
Finish boning the chicken that didn’t turn out best, keeping the legs and wings separate and intact and collecting the meat from the rest of the chicken. Use the meat in a forcemeat recipe - find one that includes chicken or adapt a favorite one to include chicken.* I think I marinated it a bit as part of the recipe, but it’s been years.
Dredge and fry the chicken livers. Stuff the boned chicken with the forcemeat. Insert the fried chicken livers about where you’d guess a chicken’s intestines would be. Use bamboo skewers to attach the second sets of legs and wings, as if the chicken had four legs and four wings. Depending on the forcemeat, you may need to bind the body of the chicken with twine to keep it from sagging into too flat a shape.
Bake chicken. It will be tricky to get the chicken and forcemeat done at the same time. IIRC, I used medium heat with a pan of water on the rack under the pan with the mutant chicken in it until the temperature of the center of the forcemeat showed that it was almost done. Then I took out the pan of water and raised the temperature to brown the skin.
I remember this dish fondly because I made it for a group camping event. I hadn’t been to the campground before. It was Rancho Seco, which turned out to be right next to here.
The mutant chicken fit.
- The forcemeat recipe will determine what kind of marinade you want to use. The herbs and spices should be compatible.
I made a cassoulet from scratch once. It took three days and my roommates loved it. (I personally thought it was kinda bland.)
Hmm, my microwave oven is 1100 watts. I better trial-and-error this. I can make a proper roux just fine on the stovetop unless I’m doing some other task too, then my ability to pay enough attention gets questionable. It’s only roux - I can scald milk, make risotto, whatever, but roux seems to get out of hand for me maybe every other time I have to look away.
Bagels are a pain. Make the sponge, let it sit for an hour. Make the dough, not too stiff, not sticky, pass the windowpane test. Form into balls, let sit for 20 minutes. Form into bagels, let sit for another 20 minutes. Try the float test; if it doesn’t work, let sit for another 20 minutes, try again. Cover and refrigerate overnight to retard the leavening effect. Boil big pot of water, boil the bagels for a minute on each side, pat dry. Brush with egg white and add toppings. Bake. Hope they don’t become bagel pancakes like my last batch. Tasty, but two days of work ended up looking like a Dali painting.
Same for me. One Thanksgiving with 18 people attending I made a huge double stuffed turkey, making the outer sausage stuffing from scratch as well baking the bread for the inner stuffing. On top of all that with soup and sides I spent hours and hours prepping the night before and cooking all day on Thanksgiving. It was a lot of work for just one meal.
Another big prep is sushi. On top of acquiring and portioning the fish, rice has to be prepared, gari has to be started well ahead of time, toasting sesame seeds and nori, making tamago, and lots of shopping to find exotic ingredients. There are sushi restaurants in town now, and all over the place, so I don’t do this as much.
Indian food can get into a big effort also, I’m always trying to make too many dishes.
Living in the heart of Cajun country (Breaux Bridge, LA) for several years made me appreciate a truly good roux. Cajun food has been the best food I’ve ever eaten anywhere, and gumbo made with a dark roux is truly something from heaven. On the other hand, some of the old hands there were starting to use prepared roux in a jar. The brand they recommended was Savoie’s And, no, I don’t work for them. 
I figure if it was good enough for them, it’s probably good enough for me, but I’ve never tried it.
Oh, and the hardest food I ever prepared was Cocoanut Creme pie (under my wife’s direction). You had to constantly stir the custard just under boiling, and Lord help you if it lumps. But, man, it was worth it.
I’ve made bagels just for the heck of it. They turned out very well, but since bagels practically grow on trees, it was a lot of time and effort that could have been put to better use. Like braided loaves of bread we made for Christmas presents one year, using three separate kinds of dough - white, whole wheat, and rye (which needed caramalized sugar for color). All mixed and risen separately. Braided to make a pretty loaf, paint with egg, bake - came out excellent, though.
Most bagels are inedible, IMO, being nothing more than bread in the shape of a bagel (sort of like hotel “croissants”, which are just bread dough), without the crisp exterior and chewy interior. Quick bagels made in a few hours are not worth the effort. I use high protein flour and malt powder; the result far surpasses anything you can find in Portland.
For whatever reason, this lasagna took an hour of nonstop work for both my mother and I working together to make. I’m glad that I was doing the actual cooking and she was chopping, because she kept trying to stop me from letting things forming a glaze on the pot so that it could then be deglazed. I won, and it was one of the most delicious things I’ve ever eaten. Too much work to make often though.
The hardest meal I’ve ever done was an over-ambitious Turkish mezze party. I made manti… and about a dozen other things. About eight hours of nonstop cooking.
Agnolotti, a stuffed pasta which I watched Lydia Bastianich make on Lydia’s Italy on PBS.
The filling was a finely chopped mixture of roast chicken, roast pork, roast vegetables, spinach, egg and cheese. I handmade the egg pasta sheets on my pasta machine.
There were three or four dozen of the plump little things, which I served in a simple browned butter and sage sauce. Mmmm good, but they were a lot of work.
A zillion ingredients, multiple prep bowls, hours (literally hours) of pre-prep/sous chef stuff, like 8 hours of cooking that required basting EVERY 15 MINUTES.
Moistest turkey I ever ate and the meat was wonderful. The actual stuffing was the consistancy of oatmeal and way too fruit-filled to be really edible.
I’d probably never make it again, but damn, the skin of the bird and meat were GOOD.
Someone made it and put up pics.
Most time consuming was Italian Easter Bread which involves 18 hours of rise time. And not 18 hours at once, 18 frequently interrupted hours. And I don’t own half the recommended hardware for making it.
It was not worth it.
That’s interesting, as the reviews seem to say the best part of the recipe is the stuffing. I love making turkey. My best results have always been the high-heat method: 475-500 for about 2 hours, depending on size. None of this slow cooking shit. (I like slow cooking, but not for poultry.)
I keep seeing it around holiday time. I might consider making it, but with dressing not stuffing, as a food safety issue. Hm, I do have a turkey in the freezer, perhaps mrAru will take a PTO day in a couple weeks and we will make it then.
Believe me, something like that is WORLDS easier without the damned kitchenaid - it was more or less designed to be made without it - and if you are just doing it by hand, you avoid all the stupid dragging the mixer out, using it for 5 minutes and then having to clean it up and put it away until the next step.
You have to make it with the stuffing in the bird or you’re making an entirely different recipe. The idea is that the zillion flavors in the (super-moist) stuffing flavor the meat. If you leave the stuffing out, it’s like making marinara sauce without tomatoes. 
What you can (and if I ever make it again, I will) do, is cook it with the stuffing in the bird, then take the gloppy, oatmeal-like stuffing (which, yeah, I share your concerns) and spread it in a baking pan and turn it into dressing.
But cooking it in the bird is a must-do, if you’re going to go for the effort.
PS–for the “onion juice”? It doesn’t exist–apparently it used to. Easiest way to fake it is to get about 4 yellow (not vidalia/sweet) onions, toss 'em into a food processor and just liquify them, then squeeze them through a strainer or cheesecloth to get the juice.