Start by dicing your avocado; place them in a large bowl and drizzle in your fresh lime juice. Gently toss to coat.
Add the tuna, onion, celery, capers, garlic, and fresh herbs.
Season with sea salt and pepper to taste, then gently toss to combine.
Best enjoyed and consumed the same day, but it's still good for about 2 or 3 days in the fridge as long as the avocado is coated with plenty of fresh lime juice.