In a large bowl, gently mash the diced avocado pieces with a fork or potato masher, leaving some chunks.
Add the onions, tomatoes, lime juice, cilantro, minced peppers, garlic, cumin, salt and pepper. Stir gently until combined but still somewhat chunky.
Taste and adjust seasoning as desired. For extra spice, add more minced pepper or a pinch of cayenne.
Allow to sit at room temperature for 30 minutes before serving to let flavors blend.
Serve immediately with tortilla chips, on tacos, in burritos, etc. Garnish with extra cilantro.
To store, transfer guacamole to an airtight container and pour a thin layer of water directly over the top before sealing. Refrigerate up to 3 days.