It's not a cold dish, but I usually grill about half the meals during the summer. It at least keeps the heat outside, and when it's really hot and sunny I hardly have to use any propane

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My wife makes this meal with chicken, onions, peppers, and tomatoes all cut into chunks and grilled. You also grill the bread. Then you let the chicken and veggies cool and put them in an avocado-pesto-type sauce, mix it up, and serve it on the bread slices. It's one of our favorite summer meals, and I think we just got it out of our Betty Crocker cook book. If anyone wants the recipe, I can post it later.
Edit: Chicken-salad croissants are really tasty too.