While your meatballs are thawing at room temperature (about 30 minutes), prepare your pineapple by peeling, coring, and cutting it into 1.5-inch chunks. Pat the pineapple chunks dry with paper towels—this helps them develop a nice char on the grill and prevents excess moisture from steaming the skewers. Soak your wooden skewers in water for at least 20 minutes if using them, which prevents burning during grilling.

In a medium saucepan over medium heat, combine the crushed pineapple, tomato paste, minced garlic, brown sugar, soy sauce, and red pepper flakes. Stir everything together and let it simmer gently for 5-7 minutes, stirring occasionally, until the sauce thickens slightly and the flavors meld. I like to taste the sauce at this point and adjust the seasoning—add a touch more soy sauce if you want more savory depth, or a pinch more red pepper flakes for heat. The sauce should be glossy and coat the back of a spoon.

Add the thawed meatballs to the glaze from Step 2 and gently stir to coat evenly. Let them simmer in the sauce for 5 minutes over medium-low heat, stirring occasionally. This brief simmer warms the meatballs through and allows them to absorb some of the glaze flavor. Reserve about 1/4 cup of the glaze in a separate bowl for brushing on the skewers while grilling.

Heat your grill to medium-high heat (about 400°F if using a temperature gauge). While the grill preheats, thread the meatballs and pineapple chunks onto skewers, alternating between them—I find starting and ending with pineapple helps contain any dripping glaze. Leave a small gap between pieces so heat circulates evenly and they cook properly rather than steam.

Place the skewers on the grill and cook for 4-5 minutes on the first side without moving them—this builds a nice caramelized exterior. Flip the skewers, brush generously with the reserved glaze from Step 3, and grill for another 4-5 minutes. During the last minute of cooking, brush the first side again with any remaining glaze. The meatballs should be heated through and the pineapple should have light char marks and caramelize slightly.