Preparation:

Bring salted water to boil in large pot, following cooking instructions on pasta package. 

Heat a large skillet on medium-high. Add lamb. Add salt and pepper. Cook lamb approximately 5 minutes each side.  Lamb may be pinkish, but should not be raw in center. Set lamb aside. 

Add rigatoni to pot. In the same skillet used for the lamb, add soy sauce, water, pineapple juice, garlic, and ginger. Bring to boil, then reduce heat to medium, add cream of mushroom soup and simmer. Add portabella mushrooms, mixing occasionally. 

Cut lamb off of bones and dice into small cubes, approximately ½-inch thick. Add lamb to sauce and pour over drained pasta.