Wash the pineapples thoroughly. Use a knife to peel the skin from top to bottom, making sure to remove all the "eyes" (cut them out diagonally to avoid leaving any hard bits that will affect the texture).

Slice the peeled pineapple into approximately 1cm thick rounds.

Then, cut the slices into roughly 1cm cubes (Cubes shouldn't be too large, or the centers won't freeze properly; nor too small, or they will turn mushy when cooked).

Place the pineapple cubes in a bowl. Add 1 tbsp of salt and enough cool boiled or clean water to submerge them. Stir well and let soak for 10 minutes (The salt water helps break down the bromelain enzyme, reducing mouth irritation, and removes some oxalic acid).

After soaking, use a slotted spoon to remove the pineapple cubes and drain them thoroughly (Draining well is crucial to avoid excess water during the next step, which would dilute the sweetness).

Place the drained pineapple cubes into a clean container. Add the white sugar (start with 50g; you can add more later to taste).

Gently toss the pineapple cubes with a spoon until each piece is evenly coated with sugar.

Cover the container (or seal it with plastic wrap) and place it in the refrigerator to marinate for 2 hours (Chilling prevents spoilage in warm temperatures and allows the sugar to dissolve slowly, letting the pineapple fully absorb the sweetness and release some of its own juice).

After 2 hours, take it out and taste a piece. If it's too tart, you can add an additional 10-30g of sugar, toss again, and let it sit for 5 minutes (to allow the new sugar to begin dissolving).

Pour the marinated pineapple cubes and all the accumulated juice into a cooking pot. Add the prepared water (just enough to barely cover the pineapple cubes).

Bring the pot to a boil over high heat, stirring gently occasionally to prevent the pineapple from sticking to the bottom.

Once boiling, reduce the heat to low and simmer for 5 minutes (Do not cook too long; 5 minutes is enough to soften the pineapple while still retaining some texture. Overcooking will turn it into mush).

Turn off the heat. Transfer the pineapple cubes along with a small amount of the syrup into a container. Let it cool completely to room temperature (This step is essential. Putting hot pineapple in the freezer can cause frost and affect freezing efficiency).

Cover the container of cooled pineapple (with some syrup) with plastic wrap. Place it in the freezer for about 4 hours. The ideal final texture is "surface frosted, interior slightly firm but not a solid block," with a shaved ice-like consistency.

Once frozen, take it out and enjoy immediately (If frozen too long and becomes a solid block, let it sit at room temperature for 5-10 minutes before eating until the surface softens slightly for a crisper texture).