Gather your ingredients. You'll need ripe avocados, ripe tomatoes (any variety you prefer), red onion, fresh cilantro (or parsley), lime juice, extra-virgin olive oil, salt, pepper, and optional additions like garlic, jalapeño, or balsamic vinegar.
Cut the avocados in half lengthwise and remove the pits. Use a spoon to scoop out the flesh from each avocado half and cut it into bite-sized chunks. Place the avocado chunks in a large mixing bowl.
Wash the tomatoes under cold water and pat them dry with a clean kitchen towel. Cut the tomatoes into bite-sized chunks or wedges, depending on your preference. Add the chopped tomatoes to the mixing bowl with the avocado.
Peel the red onion and thinly slice it into half-moons. You can soak the sliced onion in cold water for a few minutes to mellow the flavor if desired. Add the sliced red onion to the mixing bowl.
Rinse the fresh cilantro under cold water and shake off any excess moisture. Remove the leaves from the stems and chop them finely. Alternatively, you can use parsley if you prefer. Add the chopped cilantro to the mixing bowl.
Drizzle the lime juice and extra-virgin olive oil over the avocado, tomato, and red onion mixture. Season with salt and pepper to taste. Toss gently to coat all the ingredients evenly with the dressing.
For extra flavor, you can add minced garlic, finely chopped jalapeño peppers (for a spicy kick), or a splash of balsamic vinegar to the salad. Adjust the seasoning as needed.
Transfer the avocado and tomato salad to a serving dish or individual plates. Garnish with additional cilantro leaves or lime wedges if desired. Serve immediately as a refreshing side dish or light appetizer.