Think of this recipe as a base for creative experimentation. If you prefer a milder salsa, or are serving this to heat-sensitive diners, you can add a cup of chopped (or canned) tomatoes to the blender when you puree the other ingredients, and adjust the seasoning accordingly. Pulse in some chopped cilantro or oregano for a layer of freshness. Add complexity by toasting a teaspoon of cumin or coriander seeds when you toast the chilies. Up the sharpness with more lime or a few spoonfuls of vinegar, or balance heat with sweetness by adding honey or agave nectar.