Crock Pot Teriyaki Pork Tenderloin

2 tablespoons olive oil
2 pounds pork tenderloin
1/2 cup teriyaki sauce
1 cup chicken broth
1/4 cup brown sugar
4 cloves garlic, chopped
3 fresh red chile pepper, finely chopped
1/2 large onion, sliced
1/4 teaspoon black pepper