Preheat your grill to medium-high heat, 375-400°F (190-204°C).
Use a sharp knife to carefully cut the avocado lengthwise around the seed, starting from the stem towards the bottom. Try to cut through the avocado until you hit the seed, then rotate the avocado around the knife to make a complete cut all the way around.
Hold the avocado and twist it in half using both hands in opposite directions to separate them. To remove the seed, carefully strike it with the blade of your knife and turn it slightly to loosen it. Then, lift the pit out with the tip of the knife.
Drizzle or brush them with olive oil, then lightly season with salt and pepper to taste.
Place the avocados directly on the grill, cut side down, and cook for 2-3 minutes until charred. Flip the avocado quarters and cook for another 1-2 minutes until lightly charred.
Remove from the grill and let them cool for a few minutes.