1) Place the tomatoes, yellow capsicum, black beans, red onion, jalapeno peppers, and lime zest in a large bowl. Whisk together the lime juice, olive oil, salt, black pepper, garlic, and cayenne pepper and pour over the vegetables. Toss well.
2) Just before you're ready to serve the salad, fold the avocados into the salad. Check the seasoning and serve at room temperature.