Slice the avocados in half lengthwise and remove the pit. Scoop the flesh into a large bowl and mash. If using, stir in the Vitamin C powder.
Add the peppers, onion, lime juice, garlic, cilantro, salt, and pepper. Stir to combine.
Taste and adjust seasonings accordingly.
Serve with tortilla chips or vegetables.
Use the ingredients as a guideline and adjust according to personal preference. I like a lot of lime and heat. If the guacamole tastes like it's "missing something," chances are that you need to add more acidity (lime) and/or salt. I prefer using serrano peppers over jalapeños since they have a more consistent heat level.