My new place is near a Kroger supermarket that has pre-made sushi platters. This is my first exposure to sushi. I’ve been trying the different combos and liking it, though it’s a little blander than I would have expected.
Two questions;
Is the sweetish spicy cabbage type thing kimchi?
Is the green, horse radishy stuff wasabi?
Just guessing that’s what they are based on what I’ve gathered from reading about it on the internet.
Thanks in advance.
The thinly sliced sweet-spicy stuff (sometimes colored pink) is gari (pickled ginger).
The green horseradishy stuff is “wasabi” - it actually is horseradish based and coloed green, in the US you’ll only find real wasabi at a high end sushi joint.
I’ve never seen kimchi served with sushi myself - it’s (generally speaking) cabbagey, sauerkrauty, spicy - it’ll come with most any meal at a Korean restaurant.
Well, there’s your problem!
I do eat supermarket sushi on occasion, but I’ve never found any that was very good. Good enough, but not what I’d want if I wanted sushi. Do try going to a sushi place.
There is another condiment, sometimes drizzled over the whole thing, sometimes in a small cup on the side. It’s roughly the color of Thousand Island dressing without the chunks of other stuff.
What’s that called?
I’ll add that I’d also highly recommend checking out the food at a good sushi restaurant sometime, it’s miles better than the premade supermarket stuff (which to me is, at best, just OK.)
The “Thousand Island” stuff ls likely some spicy mayo-based condiment - not exactly old-school authentic 
I should add that these platters are not prepared somewhere else and shipped here frozen. There are people slicing up fish and assembling these platters behind the counter. Maybe they are still lower quality than a true sushi place but this is on the end of town most likely to have people that know the difference.
Mayonnaise is a very common condiment in Japan, even if it varies slightly from western mayonnaise, and can be sprinkled on sushi in Japan, as well as on other dishes.
I think you would find that the Kroger sushi is just as expensive as actual sushi from a restaurant and much lower quality. That has been my experience specifically with Kroger sushi.
I can’t imagine eating it unless I saw the person actually making it and I was able to get it immediately after. Sushi’s shelf life is about 10 minutes.
The first few times I tried it, I ate it while still chilled. lately I’ve been letting it get to near room temperature. Still kind of bland.
Is it blasphemy to use chili garlic sauce?
If I was to ask for a recommendation for a sushi place among my circle of friends the answer would be “Why would you eat bait?, Roadhouse has a shrimp special on Tuesday!”
Do yourself a favor. Find a good Japanese restaurant, go there, and eat sushi. Sit at the bar and talk to the sushi chef. Compare and contrast. 
I assume you’re eating rolls, right? That’s what you usually get in grocery stores. There are different kinds of sushi, (nigiri is what most people think of when they hear “sushi”-- that’s a slice of fish on top of rice, usually with wasabi in-between). But try some sashimi (just raw fish). Dip in soy sauce.
Oddly enough, where I live (NorCal) most Japanese restaurants out in the 'burbs are run by Koreans, and they usually have some spicy stuff on the menu. Most Japanese food is not spicy. Flavors are meant to be “pure”.
Try some Poke, if you can get it. It’s really a Hawaiian thing, but is basically spicy, raw tuna.
Kroger is to sushi as McDonald’s is to hamburgers. If it’s all you can get, fine, but it’s basically cardboard. Go to a real sushi restaurant.
Are you using the soy sauce? If I’m eating some from the store at home, I put soy sauce in a little cup and stir in/break up pieces of wasabi, to taste, in the sauce. It’s what you do at a restaurant. Dunk the piece of roll in that, pop the whole thing in your mouth.
FWIW and IME, most cuts of sushi are fairly delicate in flavor. There are exceptions (uni comes to mind, but you’re not getting that at a supermarket), but it’s just not terribly strongly flavored stuff, most of the time.
From what you’re saying, it sounds like you’re probably getting some of the more “western”-style rolls and the like, which often use a sort of spicy mayo stuff, as well as Sriracha. More traditional preparation is (pretty much) rice, wasabi, fish, full stop. Nothing wrong with either approach–I usually tend towards being a traditionalist myself, but I’ve been known to enjoy the western rolls as well.
Actually, the most obvious difference between supermarket sushi and good-quality sushi-bar sushi is in the texture and flavor of the rice. Supermarket sushi rice isn’t properly flavored, and it’s not as tender and sticky and it’s a bit chewy from being chilled in the refrigerator case.
And tell the chef about your experience, and that you’d like to learn what it should really taste like. He will be happy to prepare something different, based on what you like and don’t like.
If I’m having nigari, I usually ask the chef to give me what he thinks is best that day. I’ve never been disappointed.
Well I’m going to defend Kroger sushi, if you go in the daytime when the sushi chef is there you can request any special order you want. I used to get just plain tuna and salmon rolls, just the fish and rice and nori.(they did not make this except by special request).
For $5 USD I got a tray of sushi that tasted better than some restaurants and buffets, I’m not joking BTW.
Most sushi restaurants in the area I was in were grossly overpriced, they seemed to waste money on making the place look like the headquarters of the yakuza in some movie.
(glass partitions with koi swimming through, $40 USD a plate sushi? 4 ROLLS?!?)
It’s all relative. Eating shrimp IS eating bait, if you live near the coast.
That said, when we had live shrimp as bait, my grandfather would routinely take the remaining ones home after we’d go fishing, clean them and fry them up for lunch, under the theory that it doesn’t get any fresher than alive a few minutes before.
So I’ve eaten my share of bait.
As for sushi, I’d say that while the grocery store stuff isn’t terrible, it’s not particularly good either. It’s like getting roast beef at a cafeteria, while getting good sushi is more like getting prime rib at a fine dining restaurant. Same basic dish, but much different in quality and execution.