Put the flour on a plate. Put the beef in a bowl, sprinkle with the salt and pepper, and mix well. Shape the beef into small, firm balls about 1 inch in diameter; you'll get 32 to 40. Roll the meatballs in the flour, dusting off the excess.

Line a plate with paper towels. In a wok or frying pan, heat the oil on high until it's hot. Fry the garlic until browned, about 1 minute; remove and set aside. Add the meatballs and sear them on high heat, stirring and tilting the pan, until they're browned evenly and cooked through, about 5 minutes; do this in batches, if necessary. Using a slotted spoon, transfer the meatballs to the paper towel-lined plate to drain.

If no oil remains in the pan, add 2 teaspoons and fry the red curry paste so it releases its aromas, about 2 minutes, stirring with a wooden spoon to prevent sticking. Add the reserved garlic and the solidified coconut milk and then stir in the peanut butter. Cook and stir to get a smooth, uniform consistency, about 1 minute. Taste and add fish sauce, sugar, or more curry paste to taste; the sauce shouldn't be too sweet.

Return the meatballs to the pan with the sauce and simmer over low heat until they're hot, about 2 minutes. Transfer to a serving dish and garnish with the mint or basil sprinkled on top.