Prepare the meatball mixture by combining ground pork, basil, fish sauce, soy sauce, brown sugar, garlic, and red chili flakes in a large bowl.
Shape the mixture into meatballs, about 1 inch in diameter, and place them on a parchment-lined baking sheet.
Heat vegetable oil in a large skillet over medium heat. Once hot, add the meatballs in batches to avoid overcrowding.
Cook the meatballs for about 4-5 minutes on each side until golden brown and cooked through, then transfer to a plate.
In the same skillet, combine water, brown sugar, fish sauce, soy sauce, and cornstarch, whisk until smooth.
Bring the sauce to a simmer. Stir occasionally until it thickens and is glossy.
Return the meatballs to the skillet, coating them with the sauce. Cook briefly until heated through and well glazed.
Serve hot, garnished with additional basil and chili flakes, if desired.