Barbecue Spare Ribs

Serves 4.

1 tablespoon vegetable oil
1 medium onion, chopped
2 garlic cloves, chopped
2/3 cup prepared barbecue sauce
1/2 cup water
3 pounds pork spare ribs
1/4 teaspoon salt
1/8 teaspoon black pepper

Heat oil over medium heat in the pressure cooker and saut