Pat pork dry and sprinkle with 1 tsp. salt and pepper. Heat 1 tbsp. lard in a 12-inch heavy skillet over moderately high heat until hot but not smoking. Brown pork in 2 batches, turning once, 2-4 minutes per batch. Transfer to a plate.

Add remaining 3 tbsp. lard to skillet and reduce heat to moderate. Add onion, garlic and peppers and cook, stirring frequently, until onion and peppers are beginning to brown, 7-8 minutes.

Stir in paprika, tomatoes and 1 tsp. salt and cook, stirring frequently, until tomatoes have broken down and mixture is very thick, about 15 minutes.

Stir together water, sour cream and flour in a bowl until smooth. Stir into tomato mixture, bring to a simmer, stirring occasionally, until sauce is thickened, about 15 minutes.

Add pork, with any juices accumulated on plate, and simmer gently until meat is just cooked through, about 12 minutes.

Goes well served with egg noodles or buttered spaetzle. Also, it is imperative to simmer the pork very gently so that it doesn't become tough.