Preheat the oven to 400°F.
To make the meatballs, place the beans, panko breadcrumbs, onion, garlic, soy sauce, paprika, ginger, and black pepper into the bowl of a food processor fitted with an s-blade.
Pulse the machine until the ingredients are finely chopped and well-mixed, but the mixture still has some texture to it.
Roll the mixture into balls, using about 1 ½ tablespoons per ball and making them about 1 ½ inches in diameter. You should get around 16. Place them on a parchment paper lined baking sheet or in an oven-safe nonstick skillet. Lightly brush or spray them with oil.
Bake the meatballs until they're lightly browned, turning them about halfway through, about 30 minutes total.
While the meatballs bake, combine ½ cup of water with the brown sugar, rice vinegar, soy sauce, tomato paste, ginger, and pineapple in a small saucepan. Place it over medium heat. Bring the mixture to a boil, then lower the heat a bit and let it simmer for 10 minutes, stirring occasionally.
Stir the cold water and cornstarch together in a small bowl or container, then add it to the mixture in the saucepan. Bring it back up to a simmer and let it cook briefly, just until the liquid thickens.
When the meatballs come out of the oven, pour the sauce over them immediately.
Serve the meatballs as they are, or, once everything is cool enough to handle, skewer each one with a piece of pineapple on top.