fry the leeks and then
deglaze the pan with saffron
and diced tomatoes

source, 6 servings
1.5 c lentils, 1 onion, halved; 2 bay leaves, kosher salt & pepper, 5 sliced potatoes, 3 T olive oil, 2 sliced leeks, 1 clove garlic, 1 sprig thyme, 2 T smoked paprika, pinch cayenne, pinch saffron+1/4 c cold water, 1 can diced tomatoes, 2 T sherry vinegar, parsley
boil lentils in 8 c water, bay leaves, onion, pinch salt, partly covered, 20 minutes; add potatoes, boil 10 minutes; cook leeks in oil, salt & pepper, paprika, garlic, thyme, cayenne until brown; add saffron & liquid, tomato & liquid, vinegar to leeks, simmer 5 minutes; add leeks to potatoes, cook down; top with parsley, more olive oil