Step 1

Pat the tofu dry on all sides with a paper towel. Cut the tofu into 1-inch wide slabs, then cut each slab in half lengthwise. You should be left with eight 1-inch wide by 4-inch long strips. Cut each strip into quarters to create 32 cubes of tofu.

Step 2

Reserve 1/4 cup of pineapple juice. Drain the chunks.

Step 3

In a separate wide, shallow dish, combine the reserved pineapple juice, ketchup, soy sauce, vinegar, brown sugar, oil, chipotle powder, garlic powder and salt. Add the tofu to the marinade and toss to coat. Cover and transfer to the refrigerator to marinate for 30 to 60 minutes.

Step 4

Meanwhile, soak the skewers in warm water for 30 minutes. Remove just before assembling.

Step 5

Assemble the skewers: Remove the tofu from the marinade and reserve the marinade. Thread the tofu, pineapple and red onion onto the skewers, alternating ingredients. Each skewer should have 4 pieces of tofu, 3 pieces of pineapple and 3 pieces of onion. Lightly sprinkle each skewer with salt evenly to coat.

Step 6

In a small bowl, whisk together the cornstarch and 1 tablespoon cool water. Add the reserved marinade to a small saucepan set over medium-low heat. Once simmering, whisk in the cornstarch slurry and bring to a simmer, stirring often, until the marinade thickens, about 2 minutes.

Step 7

Heat a cast-iron grill pan over medium heat, about 5 minutes. Brush the pan with oil and increase the heat to medium-high.

Step 8

Brush each skewer on all sides with the thickened marinade. Grill the skewers for 6 minutes total, turning once every 90 seconds. Repeat with the remaining skewers.

Step 9

Brush the grilled skewers with the remaining marinade, if desired. Garnish with fresh cilantro and serve with lime wedges. Serve immediately.