Many of the best pasta sauces are simple vegetable dishes made by chopping the vegetables somewhat more finely than if they were being served as a side dish, then tossing the vegetables with cooked pasta. Tomatoes, chopped and gently stewed into a sauce, are the best-known example, but greens such as spinach, chard, broccoli raab, kale, artichokes, asparagus, peas, green beans, and fennel can all be cooked and used alone or in combination as simple sauces. Mushrooms and truffles are also used to make simple but extraordinarily delicious sauces.