Remove the tops and seeds from the Anaheim peppers. Roughly chop the red onion. Peel 2 cloves garlic. Cut the jalapeño pepper in half and remove the seeds (leave the seeds and/or use the whole jalapeño pepper for a spicier version). Juice 1 lime.
Char the Anaheim peppers by placing each on an open burner flame and heating until mostly blackened, turning frequently, under 1 minute per side.
In a blender or food processor, add all ingredients and pulse until combined but still slightly chunky. Store refrigerated for up to 1 week (can also be frozen for several months: defrost and stir to recombine the liquid).