Prepare the Tofu & Pineapple: Drain the pineapple, reserving all the juice for the marinade.
Cut the pineapple into 1-inch cubes; cover and chill. Press the tofu to remove excess water, then cut it into 1-inch cubes and place in a large resealable bag.
Make the Marinade: In a small bowl, whisk together the reserved pineapple juice, lime juice, olive oil, jerk seasoning, salt, and minced garlic.
Pour the marinade over the tofu in the bag. Seal the bag, turn to coat, and marinate in the refrigerator for at least 8 hours, or up to 24 hours for maximum flavor.
Assemble the Skewers: If using wooden skewers, soak them in water for at least 30 minutes to prevent burning.
Drain the tofu, reserving the marinade for basting. Alternately thread the tofu, pineapple chunks, onion wedges, and sweet pepper pieces onto the skewers, leaving a small space between each piece.
Grill: Preheat your grill to medium heat and lightly coat the grates with nonstick spray.
Place the skewers on the grill and cook for about 8 minutes, turning to brown all sides and brushing occasionally with the reserved marinade. The skewers are done when the peppers are crisp-tender and the tofu has nice char marks.
Don't Crowd the Skewers: Leave a small space between each piece of tofu, pineapple, and vegetable. This allows heat to circulate evenly, giving you a perfect char instead of steaming the .