Cauliflower or Brussels Sprouts sometimes taste slightly bitter after cooking. Is this some mistake in the way they are cooked or is that just the vegetables themselves?
All the vegetables form the Brassica family have a bitter component to their flavour. Brassica is the family that includes cauliflower, cabbage, broccoli and Brussels sprouts.
You can actually remove quite a lot of it by leeching it out in to the water, or by using salt. Remember that this means you're also losing some of the nutritional value, though that doesn't matter too much.
You can also try ot mask the bitter taste with the sauce/dressing. Something like a cream sauce, or even barbeque flavour will usually mask the bitterness quite well, while letting the cabbage-ness come through.
Don't overcook your cruciferous vegetables. Or cook them with flavors that will mask it better -- garlic, olive oil, salt, hot chilies, etc.
When you overcook them you release more aromatic compounds and aromas.
Also, you may be sensitive to phenylthiocarbamide (PTC). Similar compounds exist in cruciferous vegetables and therefore for some people they can taste radically bitter while for others there's no noticeable bitter taste.
Sources: http://www.goodeatsfanpage.com/season8/lettuce/greens.htm http://en.wikipedia.org/wiki/Phenylthiocarbamide
Coat lightly with olive oil, sprinkle w/ balsamic vinegar, liberal application of kosher salt, and fresh cracked pepper in a bowl to coat evenly. Then spread 1-layer thick on sheet pan.
Roast in the oven, ~35 min 375 degF.
The veg will develop a light caramelization on the outside in some places, but will have a sweeter flavor.
This works well for brussel sprouts, asparagus, green beans or cauliflower.
CAULIFLOWER doesn't have to taste strong. I steam it in the liners from cereal boxes in the microwave. Just cut the cauliflower into a bit larger than bite-size pieces, place them in the bag and run water into the bag. Pour out the water, then fold the end of the liner under and pat the veggies so they are level in the bag. Steam it for about 3 minutes in the microwave for a 3/4 filled bag. NOT bitter at all. Add cheese sauce over it when serving.
Also SPINACH is devine cooked this way. Omit pouring the water into the bag. Just steam it for a couple minutes. Then put butter and salt and pepper on it. Yum. I also steam CORN ON THE COB, BROCCOLI, and SLICED YELLOW SQUASH this way. The timing for corn on the cob is 3 minutes per ear. Broccoli, the same as cauliflower, and squash a couple of minutes. I've been doing this for 25 years and am very healthy.