Trim top and bottom of the pineapple with a sharp chef's knife. Stand the pineapple upright and slice off the rind in vertical strips, following the curve of the fruit. Remove the remaining “eyes” by running the tip of the knife diagonally in shallow V-shaped grooves, or remove with a small paring knife. Cut the pineapple into 8–10 wedges (or 1/2-inch thick rounds if preferred). Pat pieces dry with paper towels to remove surface moisture so glaze adheres and grilling is even.

Glaze

Make the glaze

In a small saucepan over medium heat, combine brown sugar, butter, lime juice, rum (if using), cinnamon, ground ginger, and salt. Stir constantly until butter melts and sugar dissolves, about 3–4 minutes. Bring to a gentle simmer and cook 1–2 minutes more until slightly thickened and glossy. Remove from heat and let cool 2 minutes.

Taste and adjust

Taste a small amount of glaze and adjust acidity or sweetness as needed: add a little more lime juice for brightness or a pinch more salt to balance. Keep warm; if glaze thickens too much, whisk in 1 teaspoon warm water to loosen.

Grilling & Finishing

Preheat grill

Preheat a gas or charcoal grill to medium-high (about 400–450°F / 200–230°C). If using a grill pan, heat over medium-high on the stove. Oil the grill grates lightly with neutral oil to prevent sticking.

Brush pineapple with oil

Lightly brush both sides of pineapple wedges or rings with the neutral oil to promote even charring and prevent sticking.

Grill pineapple

Place pineapple pieces on the hot grill in a single layer. Grill 3–4 minutes per side until pronounced grill marks appear and the fruit begins to caramelize. Brush the cut side once with about 1 tablespoon of the warm glaze halfway through grilling that side, then turn and grill the other side. Total cook time per piece should be 6–8 minutes depending on thickness and heat.

Finish with glaze

During the last 1–2 minutes of grilling, brush both sides generously with remaining glaze and allow it to set and caramelize briefly—watch carefully to avoid burning (sugar can char quickly). Remove pineapple from grill and transfer to a platter.

Sprinkle finished pineapple with flaky sea salt if using, and garnish with fresh mint leaves. Serve warm with lime wedges for squeezing over the fruit.