Vegetables:
Most above-ground veggies are best cooked with steam rather than in boiling water. Less of the flavour is leeched out and the texture is more pleasurable to the palate. Some root veggies are better cooked this way, too. In most cases, a bit of sugar brings out the flavour, especially with carrots and peas. A bit more cooking time is required but the taste is well worth the effort.
A few of our favourites, peas, beans, cauliflower, broccoli and Brussels sprouts are unbelievably improved by steaming and adding just a bit of sugar during cooking. Cabbage, being sweet, responds well to this approach, as it truly blossoms in taste and colour.
One of the most important aspects of cooking with water in any form is the water itself. Regular tap water destroys the color and flavour of everything it touches, even as steam. Distilled water is a far better cooking liquid, as all minerals have been removed. I know it tastes terrible to drink; it's flat! Another good cooking water is Reverse Osmosis water. Most of the minerals are removed during the process, thus providing a neutral cooking liquid.
In using these types of water, you'll find the colours are more appealing and the taste is greatly improved.
Cooking in water:
Due to the temperatures outside, in winter, we tend to cook a lot more in the way of soups and stews. Of course, one of the major ingredients is water. The quality of the water makes a major difference in the flavour of the final product. If you don't like the taste of the water you drink, why use it for cooking? Most bottled waters are no better than average tap water. Read the label. If they added minerals to make it palatable, then don't use it to cook with. You want the herbs and spices to do their job without competing with chemicals in the water.
Potatoes, rice and pasta are our major source of cooked starch (bread is something most of us buy, already cooked) and the flavour is changed by the minerals in the water. Salt is the first thing we add to improve the flavour. Adding a bit of onion in the potatoes, while boiling them, makes a pleasant difference in the final result for boiled or mashed potatoes. Of course, butter adds a lot of flavour and improves the texture of potatoes no matter how they're cooked or served. Most starches are very neutral and absorb flavours readily. Controlling those flavours is as much a part of cooking, as knowing which spices to use and what temperatures to cook things at. We all know the basic "salt and pepper" part of cooking. Moving beyond that to being a creator, rather than a cook, is understanding the effect of how we cook.