Heat the lard in a deep frying pan with a lid. Sauté the pork fillets for 5-6 minutes from both sides.
Add the onion, garlic, a pinch of salt and sauté for 5 minutes; stir.
Season with the salt, pepper, and pure warm water; stir. Cover the pan and cook for about 30-40 minutes over medium-low heat. (cooking depends on the thickness of the pork).
Sprinkle the oregano and basil, mustard dissolved in 1/2 cup of warm water and shake the pan to incorporate all ingredients well. Simmer with an open lid for 5 minutes.