seafood salad recipe

1/2 pound cooked shrimp, peeled and deveined - 1/2 pound cooked crab meat (or imitation crab meat) - 1/2 pound cooked calamari, sliced into rings - 1 small red onion, thinly sliced - 1 cup cherry tomatoes, halved - 1 cucumber, diced - 1 avocado, diced - 1/4 cup fresh cilantro, chopped - 2 tablespoons capers - 1/4 cup olive oil - 2 tablespoons lemon juice - 1 tablespoon white wine vinegar - 1 teaspoon Dijon mustard - Salt and black pepper to taste