This cucumber tomato avocado salad is a simple and refreshing gluten-free side dish that is great for weeknight meals and entertaining, too. A potluck staple in our house during the summer, it pairs so well with all types of protein - from seafood to meat to vegetarian and vegan options. The tomatoes, cucumbers, and avocado have great texture and flavor and are coated in a lemon dressing and topped with flavorful chives.