In a hot frying pan with a tbsp of olive oil, sauté the onion and tomato. Gently plop the beef into the sautéed onion and tomato. Season with pepper, salt, paprika, and any other spice of your choice. Sear for 7-10 minutes over medium-high heat.
Lay the lettuce leaf on a flat board. Scoop out some of the cooked beef and place this on one side of the leaf. Top with avocado and sour cream. Roll the leaf firmly. Repeat until all of the ingredients are used up.