Belgian Beef Stew

2 pounds beef short ribs
1/2 teaspoon salt
1/2 teaspoon pepper
3 tablespoons all-purpose flour
2 tablespoons vegetable oil
2 tablespoons butter
2 medium size onions (about 3/4 pound), finely chopped
1 (12 ounce) bottle dark beer
1/2 cup double-strength condensed consomm