Roll meat in flour, and fry in hot lard till it reaches the color of a seared steak. Remove meat.
Fry onion slices in lard remaining in the pan till slices become golden.
Remove onion from fat with slotted spoon and put in a heavy casserole. Add paprika and salt to taste; mix.
Place fried meat and spinach in the casserole with the onion; add ½cup water. Cook, covered, over a very low heat for 1 hour or longer, until lamb is tender. Check several times to see if additional water is necessary, but each time only add ¼cup water.
When meat is cooked and spinach becomes totally disintegrated, like a sauce, mix in ricotta and sour cream. Simmer for a few minutes. Serve with rice pilaf.