When choosing zucchini at the store or farmer’s market, look for zucchini that are about 6-8 inches long. That’s a good mature size without being overgrown. Overgrown zucchinis are certainly edible, but they tend to become tough and fibrous. They should be firm to the touch and the skin should not contain and cuts or blemishes.
Store leftovers in an air-tight container kept in the refrigerator for up to 3 days. Reheat in the microwave or on the stovetop with extra butter or olive oil.