Place the jalapeño peppers and onion segments in a pot and cover them with water. Bring the water to a boil and cook for about 10 minutes, or until both the jalapeños and onions are softened. Remove the jalapeños from the water and cut off their stems. Reserve a small amount of the boiling liquid for the next step.

Transfer the boiled onion segments, stemmed jalapeños (from Step 1), vegetable oil, salt, black pepper, garlic powder, and the juice from one lime wedge into a blender. Add a small splash of the reserved boiling liquid to help blend. Puree the mixture until it is smooth. Taste and adjust seasoning as needed. I like to use just enough of the boiling liquid so the salsa pours easily, but stays creamy and thick.