In a medium bowl, mash the avocados with lime juice, salt, and black pepper until smooth but still slightly chunky. Stir in the red onion, tomatoes, and cilantro until well combined.
Lay an egg roll wrapper on a clean surface with one corner pointing towards you. Place about 2 tablespoons of the avocado mixture in the center of the wrapper.
Fold the bottom corner of the wrapper over the filling, then fold in the sides and roll it up tightly. Seal the top corner with a little water. Repeat with the remaining wrappers and filling.
Heat about 2 inches of oil in a deep skillet or pot over medium heat until it reaches 350°F. Carefully add the egg rolls in batches, frying until golden brown, about 3-4 minutes per side. Remove and drain on paper towels.
For the dipping sauce, mix the sweet chili sauce, soy sauce, and rice vinegar in a small bowl until well combined.
Serve the warm egg rolls with the sweet chili dipping sauce on the side.