Cooking Fresh & Frozen Veggies- Keep those nutrients! If vegetables are cooked in too much water for too long a time the all-important vitamins and minerals will pass into the water and go right down the drain. Bye bye nutrients! Cook fresh and frozen vegetables in as little amount of water as possible. Add water to the saucepan to just barely cover the vegetable. Bring to a boil quickly and boil gently, cooking just until tender. Hello vitamins and minerals!