When: May through September, although since red peppers are actually mature versions of green ones, you may not see them in markets until later in the season.
Why: While all peppers are very low in calories (about 25 per cup), reds—which taste sweeter and milder—are best for you. They contain 11 times more beta-carotene than green bell peppers, and while the green variety delivers 60 percent of the recommended daily value of vitamin C, red gives you 240 percent.
How: Dip them in hummus now; roast them in big batches for salads, grilled cheese sandwiches and snacking later (they'll keep for a few weeks in the fridge). Or try them in vegetarian sloppy joes or sautéed with ginger, garlic and chili for a vibrant side.