Mix the milk with salt and black pepper. Dip the extremely well-cleaned frog legs in the milk mixture and then in the flour.
Heat the oil, add 3 1/3 tbsp (50 g) of butter and fry the legs until they redden (around 12 - 14 minutes). Once the legs are fried, pour on the lemon juice, add the finely diced parsley and the garlic, which we fried using the remaining butter.
Garnish the dish with lemon slices, and pour on the butter used to fry the garlic and serve while still hot.