Heat grill to medium-high heat. Run 2 thin metal or soaked bamboo skewers parallel through each onion slice, placing skewers about 1½” apart to keep slice intact. Liberally brush both sides of onions rings, eggplant slices and tomato halves with olive oil. Sprinkle with Adobo. Grill, flipping occasionally, and brushing with more olive oil, until vegetables are tender and caramelized,4-6 minutes for tomato, 12-14 minutes for eggplant and 18-20 minutes for onion . Thinly slice vegetables.
In medium serving bowl, gently fold together grilled vegetable slices, pimiento slices, garlic, and ¼ cup olive oil. Serve warm or at room temperature.