1. To make the peanut sauce, heat the vegetable oil in a small saucepan over medium heat. Add the curry paste and cook for 30 seconds, until fragrant. Stir in the peanut butter, brown sugar, and lemon juice, then gradually stir in the coconut milk. Bring to a boil, reduce the heat to low, and simmer for 5 minutes, or until thickened. If it becomes too thick, stir in a little water. Keep warm.

2. For the meatballs, combine the ground beef, cilantro, curry paste, lemon juice, fish sauce, lemongrass, egg, and garlic, and season with salt and pepper. Roll the mixture into small balls about the size of a walnut. Dust each meatball with the rice flour.

3. Heat enough oil to come halfway up the sides of a large frying pan and heat over high heat until the oil shimmers. In batches, fry the meatballs for about 3 minutes, until browned and cooked through. Using a slotted spoon, transfer to paper towels to drain. Serve hot, with the warm peanut sauce and lime wedges.