I have gathered, below, all the various methods for cooking vegetables with step by step images.
Brief preliminary cooking, or even complete cooking, in boiling water to which salt or lemon juice has been added. Leaf vegetables can be cooked in this way, and whole cabbage leaves are easier to roll and stuff after blanching. After the vegetables have been added, the blanching time is calculated from the time when the water returns to the boil. Depending on the quantity of vegetables immersed and their consistency the water may go off the boil when they are added. You may need to blanch vegetables in several batches.
Cooking quickly in hot, preferably non-saturated vegetable fat or oil in a frying-pan. Following the recipe instructions, cut the vegetables up into small pieces of equal size. Vegetables with a high moisture content should first be dipped in flour or a light coating of breadcrumbs. If vegetables are cooked in breadcrumbs, the cooking liquid should be drained off; a spicy sauce should be offered instead.
Cooking in a colander or vegetable steamer over boiling water. Pressure cookers are ideal for steaming, allowing the vegetables to cook under hermetically sealed conditions. The food being cooked must not come into contact with the water below, and the lid must fit as tightly as possible. As nutrient’s will still be absorbed into the boiling liquid, use this for a sauce or soup.
Cooking over a low heat in a small quantity of fat and liquid. The liquid may be produced by the food being cooked, e.g. from vegetables with a high moisture content such as many of the leaf vegetables, mushrooms, tomatoes, courgettes or onions. When using this method try to avoid lifting the lid. Move the contents around by shaking the saucepan. Only add liquid during cooking if absolutely necessary – possibly if you are cooking larger quantities of vegetables.