Place the potatoes in the microwave oven and cook on high for 4 minutes, until slightly soft. Let the potatoes cool for a few minutes, then cut in half. Place the potatoes in a plastic bag and drizzle with the olive oil and garlic, then sprinkle with the salt. Twist the bag to seal, allowing some of the air to remain in the bag. Toss gently to coat the potatoes evenly.
Remove the potatoes from the bag, place on the grill for 5 minutes. Turn the potatoes and continue to grill for 5 more minutes. Turn the potatoes again and grill for about 5 additional minutes on each side, until the potatoes are fork-tender and lightly browned.