1 c. navy beans
4 c. water
1 lb. ham bone
1 onion, chopped
2 carrots, sliced
2 celery ribs, chopped
1/8 c. minced green pepper
1/2 c. tomato puree
1/8 tsp. dry mustard
1 clove
2 peppercorns

Soak beans overnight. Drain. Place all ingredients in pressure cooker. Cook 30 minutes with pressure regulator rocking slowly. Let pressure drop of own accord.

Alternatively: Simmer all ingredients 2-3 hours, until beans are tender.