Scoop flesh from 4 avocados into a medium bowl; mash with a fork until mostly smooth.
Add ½ cup cilantro, ⅓ cup onion, ¼ cup lime (or lemon) juice, 1 tablespoon oil, ½ teaspoon salt and pepper to taste; stir to combine.
Season with hot sauce, jalapeños, cayenne and/or chipotle, if desired.
