Clean the grill grates thoroughly and oil them to prevent the apples from sticking. I usually dip a folded paper towel in cooking oil and use tongs to rub it across the grates.
Preheat your grill to medium-high heat (around 375-400°F/190-205℃). If you're using a charcoal grill, ensure the coals are evenly lit and glowing.
Remove any stickers from the apples and wash them. Place them on the cutting board, remove the stems (if any), and core them.
Cut each apple into thick slices or wedges. If using small apples, split them in half.
Combine the water and lemon juice in a bowl. This mixture will help prevent the apples from browning.
Place apple slices into the lemon-water mixture so they are submerged in water. This step helps keep the apples from turning brown.
In a small bowl, add the brown sugar, ground cinnamon, allspice, and salt. Mix well to ensure an even distribution of the ingredients. Adjust spices to taste.
Remove apple slices from the lemon water and thoroughly pat dry with paper towels.
Brush with melted butter and quickly sprinkle the cinnamon mixture over both sides of the apples until evenly coated.