Beets. They taste like shit, but do awesome stuff for me when I go on long bike rides.
For flavour, I really like grilled brussels sprouts, asparagus, and zucchini (not a vegetable though). If we're talking uncooked then bell peppers, carrots, and peas in the pod are all pretty good.
Tomatoes are great too . . . but they aren't vegetables. :P
In Nix vs. Hedden, 1893, the U.S. Supreme Court ruled that tomatoes are vegetables for legal purposes, following the "ordinary meaning" of vegetable rather than the "botanical meaning." This debate has been going on for a very long time!
I have been converting beet-haters to beet-lovers with my borscht recipe for 20 years now. That said, occasionally you do just get a bite of bitter beet... there's a whole poem about it.
You can't just throw this out there without sharing now....(the recipe not necessary the poem)
The thing is, a friend brought the recipe back from Russia 20 years ago, it wasn't translated particularly well, and I probably haven't looked at the actual recipe for 15 years. I made it vegetarian for years, then started putting the meat back in. At this point, it's more of a rough guideline. But my version is roughly: 1 kg of ground meat, 3 beets, 2 carrots, 1 onion, 3 potatoes, and a bell pepper, with 2-3 cloves of garlic, 1 tsp pepper, 1 Tbsp soy sauce, and 1 Tablespoon of sorghum or molasses or 2 tsp sugar*.
I skin and chop the beets and the pressure cook them for 2 minutes with 6 cups water, 1 tsp salt, and 1/4 cup of vinegar. While that's going, I saute the meat, then saute the carrot and onion in the fat from the meat. Once that's done, I put everything into the same pot, add about a quart of broth, usually 1-2 tsp more salt or some Better Than Bullion, add another 2 Tablespoons of vinegar, and boil until everything is tender. Then you put a spoon of sour cream in the bowl when you eat it.
The essential bits of this are: boil the beets with vinegar, make a vegetable soup, add sour cream at the end.
*I do remember that the original recipe called for even more sugar than this. Whether you need sugar at all really depends a lot on whether your beets are young and sweet or old and woody-- sometimes I buy large bags of beets and they definitely benefit from added sugar; fresh beets, not so much.
The original recipe also called for twice as much meat. I think it just said, "1/2 kg beef, 1/2 kg pork." I asked the guy who brought the recipe back (and then asked me to make it, because he couldn't cook), "What kind of meat did they use? Chunks? Shreds? Ground?" and he said he had no idea... I think I had ground beef in the fridge at the time, so that's what I used. About a hundred years later, I had borscht from a bubble waffle stand in Cambridge and the Ukrainian lady who made it told me that borscht is Ukrainian, not Russian at all, and her version had tomatoes, red kidney beans, and green beans in it.