THERE ARE TWO SECRETS TO PREPARING A REFRESHING, wholesome supper without turning on the stove: Build your meal around garden-fresh produce, which gives you flavor, fiber, and valuable vitamins and minerals. Then add energizing lean protein that doesn't need cooking, like canned beans or frozen cooked shrimp. To show you what we mean, here are six hot-weather recipes you can use to get a nutritious meal on the table--and keep your cool.