Heat oil in a small saucepan over medium heat. Add garlic and ginger; sauté 30 seconds until fragrant. Don’t burn them, they’re drama queens.
Add pineapple dice and cook for 2–3 minutes, giving them a little caramelization for depth.
Pour in pineapple juice, soy sauce, and lime juice. Let it simmer gently for 4–5 minutes to mingle flavors.
Stir in the cornstarch slurry and cook another minute until the sauce thickens to a glossy consistency. If it’s too thick, splash in a bit of water.
Season with salt and pepper to taste. Taste, adjust, and resist the urge to add three more ingredients just to prove you’re fancy.
Remove from heat and spoon warm sauce over cooked fish, or serve on the side for dipping. Optional: simmer a few extra pineapple bits in there for texture pockets.
