Dice the avocados and immediately place them in a large bowl.
Pour fresh lime juice over the avocados and gently toss to coat all pieces to prevent browning.
Add the halved cherry tomatoes, thinly sliced red onion, and chopped cilantro to the bowl.
If using any optional ingredients (jalapeño, black beans, cheese, bell peppers, cucumber, cumin, or garlic), fold them in now.
Add the mixed greens to the bowl.
Season with salt and pepper to taste.
Gently toss all ingredients together, being careful not to crush the avocado pieces.
Serve immediately or chill for up to 15 minutes before serving for best results.