1 lime, halved
1/2 medium-size red onion, chopped
2 to 3 medium-size tomatoes, chopped
1/4 cup (about a palmful) cilantro or flat-leaf parlsey, chopped
Salt and freshly ground pepper
Scoop the avocado halves out of the skin with a spoon and place them on a plate. Squeeze 1/2 lime over them to keep them from turning brown.
In a bowl, add tomatoes, red onion, cilantro, salt and pepper to taste, and the juice from the other half of the lime. Toss to combine.
Spoon tomato mixture over the avocado and serve.