Set grill to medium-high heat.
Slice the avocados in half, remove the pits, and drizzle the flesh of each half with olive oil.
Cut the onions into two or three ½ inch slices as if they were for onion rings, but keep them together.
Slice the jalapeños in half length-wise then remove the stem, seeds, and ribs.
Cut the limes in half displaying the segments.
Grill the tomatillos, jalapeños, onions, garlic, and limes for 5-10 minutes, checking them constantly for dark grill marks, then remove and set aside once.
Grill the avocados cut side down for approximately 3 to 4 minutes or until grill marks form. Remove from the grill and set aside.
Carefully remove the flesh of each avocado by scoring the grilled side with a knife into a grid, then scooping it out with a spoon into a large bowl.
Remove the skin from the garlic cloves and then mince. Rough chop the tomatillos and dice the jalapeños. Add to the bowl with the avocados then squeeze with the grilled limes and add the salt, pepper, and cumin.
Using a potato masher (or fork), loosely combine everything, stopping when you achieve the final texture you're looking for.
Sprinkle the salt, pepper, and cumin over the top then fold everything together with a spatula.
Serve with your favorite tortilla chips.