If you're using dried chilies in your salsa, toast them in the microwave for about 20 seconds to improve their flavor.
To give your salsa a deep charred flavor, blister the skins of fresh peppers, tomatoes, tomatillos, and aromatics using a broiler, a cast iron skillet, an open flame, or a torch.
Char Your Vegetables for More Flavorful Salsa and Chili
Salt your chopped tomatoes to give them superior flavor, appearance, and texture in your salsa or guac.
How the Science of Salt Can Improve Your Tomatoes