Pre-heat your broiler to high with a rack on the very top. Spread the jalapeños evenly on a baking sheet and toss in a little oil and broil until charred on all sides.
Place the jalapeños in an air-tight container or bowl covered with plastic wrap and let sit until cool. Meanwhile, lower the broiler to low and place the garlic on a baking sheet and broil until browned.
Peel the skin off the jalapeños and remove the tops. If you want your salsa less spicy, remove all or part of the seeds and veins.
Blend the jalapeños and garlic in a blender. Then drizzle in oil while blending until smooth. I don't have a fancy blender so mine didn't get as smooth, but still delicious. Blend in lime juice to taste. Store leftovers covered in the refrigerator for up to 5 days.