Add the canned tuna, mayonnaise, mustard, capers, celery, onion, capers, lemon juice, fresh herbs, garlic powder, and a pinch of salt and pepper to the tuna in the mixing bowl.
Stir everything until well combined and give the tuna salad a taste. Adjust the levels of salt and pepper to fit your tastebuds and then either serve immediately or place the tuna salad in an air-tight container in the fridge.