Heat grill to high. About 300 degrees. Brush pineapple slices with olive oil or spray with cooking spray. Grill 5 minutes per side, until nicely browned. We like ours charred a bit for extra flavor! Remove and allow to cool to room temperature. Once cooled remove core, dice and set aside.
Cut avocados in half lengthwise. Remove pit and scoop flesh from its shell into a bowl.
Add lime juice and salt and mash lightly with a fork.
Add onion, peppers, cilantro, garlic and pineapple. Mix well.