Leafy Greens

• It's best to cook leafy greens in a steamer rather than a pressure cooker because it doesn't take long for them to grow tender. Steaming is especially recommended for delicate leafy greens such as spinach and mizuna, which only take a minute or two to fully cook. Hardy greens such as collards and kale take longer and can even stand up to pressure cooking for short periods. However, their cooking time is still short enough that their texture and flavor will be more appealing if you avoid the intensity of a pressure cooker.

Root Vegetables

• Root vegetables tend to be quite hard, and it takes time and heat to soften them. You can certainly steam root vegetables, especially if you cut them into bite-size pieces so they cook more quickly. But you can also pressure cook them, especially if you want to save work and cook them whole, or if you're preparing a dish for which they should be very soft, such as mashed potatoes.

Summer Squash

• Summer squash such as zucchini, yellow squash and pattypan take relatively little time to cook, and they grow mushy and unappealing if they are overcooked. Cook summer squash in a steamer until it is just tender. Also observe the color of the squash when you remove the lid to check for done-ness. If the color of the outside skin is bright and vibrant, your summer squash is either done or almost done. A summer squash with a skin color that has started to grow dull is already overcooked.

Winter Squash

• Winter squash is harder and hardier than summer squash. Unlike summer squash, which can be eaten either raw or cooked, winter squash should always be cooked until it is completely soft. Because it must be fully cooked, winter squash can be prepared in a pressure cooker. However, it may be cooked in a steamer as well, although this method may take at least 30 to 40 minutes.