Southwestern Flank Steak

1 1/2 pounds flank steak, cut in half
1 tablespoon vegetable oil
1 large onion, sliced
1/3 cup water
4 ounces chopped green chiles
2 tablespoons vinegar
1 1/4 teaspoons chili powder
1 teaspoon garlic powder
1/2 teaspoon granulated sugar
1/2 teaspoon salt
1/8 teaspoon pepper

In a skillet, brown steak in oil; transfer to a crockpot.

In the same skillet, saut