This salsa is a little spicy, intensely flavorful, a little sweet, and a touch tart. If you want a to taste authentic Mexican flavors at home, this is a good place to start.
Preheat the oven to 450°F/230°C. Stem and seed 20g (3-4) guajillo chiles, 5g (1/2 of 1 large) ancho chile, and 2g or 3–5 chiles de árbol. Tear the de-seeded chiles into 2” chunks
Heat a dry pan and toast chiles over medium heat, stirring frequently, until they're fragrant, about 2-3 minutes. Once toasted, add about a quart (4 cups) water, turn off heat, and soak for 15 minutes. Be sure to reserve 120g (1/2c) chile soaking liquid before draining
Spread 200g halved tomatoes, 275g halved tomatillos, 50g white onion, and 10g garlic cloves on a parchment-lined sheet tray. Roast at 450°F/230°C for about 15-20 minutes or until everything's browned, blistered and softened. If at this point, the veggies haven’t taken on adequate browning, return them to the oven under a high broiler for about 2 minutes to catch some char.
Transfer roasted veggies and their juices into a blender jar along with the strained soaked chiles, 10g white vinegar, 8g salt, and 2g sugar. Cover and let stand 10 minutes to steam and cool slightly.
After the 10 minute steam add the reserved Chile liquid (or use water if If chili liquid tastes bitter) to the to the blender, cover, and spin until it's smooth but with a little bit of remaining texture.
Heat 2 to 3 tablespoons of neutral oil in a saucepan over medium heat until hot and shimmering. Pour in the blended salsa and cook, stirring often, for 90 seconds to 2 minutes.
Stand back and use caution when pouring salsa into the oil. It will spit and splatter when pouring and while cooking .
Pull it off the heat, transfer to a wide bowl, and cool in the fridge.
Notes
Serve this salsa on tacos, grilled meat, eggs, or anything fatty that needs heat and depth. It's also great as a dip for tortilla chips if you like a more deeply flavored, smoky salsa.