Coat the shrimp evenly with melted butter in a bowl.
Preheat a skillet over medium-high heat. Place the shrimp in the skillet in a single layer, searing for about a minute until the edges start to turn pink. Flip the shrimp and cook for less than a minute until fully cooked.
Move the shrimp to a plate and let them cool.
In a large mixing bowl, combine avocado, tomato, the white onion, and parsley. Drizzle with olive oil and lime juice, then toss to combine.
Add the cooled shrimp and stir gently to mix. Add salt and pepper in the salad for extra taste.