None at all really, I can’t handle spicy. If it tasted even mildly hot to me, or caused that burning kind of feel, I would just eat around it. But I get nothing. Except an extra red tongue.
Agree with dragon fruit and fresh mozzarella. I register hardly any taste.
Chapulines – toasted grasshoppers. In Oaxaca, there are old ladies selling them nearly everywhere you turn, from wee ones the size of wheat grains all the way up to big scary ones an inch or so long – and they all taste of nothing other than chili powder and the grease they were cooked in. It’s like eating puffed rice with a light sprinkling of chili.
Chayote squash-popular in Mexico, tastes like dish water.
My wife juliennes it and stir-fries it with soy sauce. So I assumed it tasted like soy sauce. 
My vote goes for Watermelon. I like things that are watermelon flavored, but personally, any time I have eaten it, I taste nothing. Simply water.
Watermelon definitely has a flavor, one I don’t like. I Aldo can’t stand the smell of watermelon-flavored things, like chewing gum.
How do you know?
Eggplant
I have that same opinion of eggplant. People always say “oh, but if you do so-and-so and blah-blah to it. . .” If I have to do all of that, then it isn’t worth eating. And it has a mushy consistency that I don’t like. I do like avocado, though, but it’s a temperamental vegetable that has to be just the right ripeness.
Actually, a lot of things are fairly tasteless, but provide a medium for something good: potatoes, white bread, hamburger buns, biscuits.
Not sure if anyone has mentioned this yet…
Yeah, plain matzoh is dry and tasteless, BUT…
Try Egg matzoh, if you can find it in the store. Has a modicum of flavor, and isn’t so dry. Much more palatable when eaten plain. Not sure if it’s kosher for Passover, though.
OR: Better than peanut butter, try haroset or charoset (English spelling varies). Mixture of chopped nuts, apples or other fruit, cinnamon, wine, other goodies, to put on your plain matzoh. Yum! For the little kiddies, this is what makes the whole seder worthwhile! See Charoset - Wikipedia
– Senegoid
Cucumbers, celery, white bread and rice are all pretty tasteless. Eggs that aren’t made with tomatoes, salsa, hot sauce or soy cheese.
According to my taste buds, the only food with no taste is white rice.
Totally agree on the rice cakes, you absolutely have to have the flavoured versions of those. Unfortunately the flavoured ones often seem to be flavoured with unhealthy stuff, like the pizza flavour ones that my local supermarket sells.
I find the discussion about strawberries interesting. Swedes, almost to a man, insist that Swedish strawberries are the best in the world and scoff at the idea of eating foreign ones. Now I wonder if the foreign strawberries are either suffering on the trip up here or we just get sent the crap ones anyway, meaning Swedish ones are going to taste better than the other stuff in supermarkets. I’ve no idea myself, since turning diabetic in 1993 my ability to eat really sweet/sharp things has diminished drastically. As such, I can’t stand strawberries.
Oh and my mum made something with marrow once when I was a kid. At the request of the entire family the experiment was never repeated. A tasteless mush.
See the main reason I like table water crackers and rice cakes is because they have essentially no flavor. I use them as a base for other flavors.
One favorite for table water crackers is a thin slice of an aged cheddar, a schmear of chutney and a slice of apple. I could go through a platter of them, but unfortuantely being diabetic I can’t 
but they are an extremely popular hors d’oeuvre around here.
My goddaughters swear by rice cakes with peanut butter, honey and alfalfa sprouts. That is one of their favorite afternoon snacks. I hate peanut butter, but rice cakes with nutella is quite good.
Nutella on rice cakes is also a great firecracker.
firecracker?
Huh. I’ve never thought of all these foods as being tasteless. I’ll agree with water chestnuts as being tasteless, and possibly tofu. I like both of them, though, as well as most of the other bland foods mentioned here.
I actually am not hugely fond of celery because I find the taste to be so strong.
I do medical marijuana and I prefer not to smoke, edibles have a longer uptake and longer more gentle action. Firecrackers are marijuana added to something such as peanut butter spread on a cracker and baked. I happen to hate peanut butter but nutella is a good substitute.
I just had a Watermelon the red part tastes sweet and watery the whitey part is just water flavor, taste nothing like a jolly rancher.
Matzo taste of cardboard with butter on it.
Dead babies are pretty tasteless…