Spicy Southwestern Steak Sauce

1 TBS vegetable oil
2 medium jalapeno chilies, stemmed, seeded, and minced
3 cloves garlic, minced
1 1/2 tsp. ground cumin
1/2 cup dry white wine
1/2 cup beef stock
1 medium tomato, peeled, seeded, and finely diced
4 TBS well-chilled butter, cut into 4 pieces
1 TBS fresh cilantro, minced

Heat oil in skillet over low heat. Add chilies, garlic, and cumin and stir 30 seconds. Increase heat to high. Stir in wine and bring to a boil, scraping up any brown bits. Cook until reduced to 2 TBS, stirring constantly, about 2 minutes. Add stock and boil until reduced to 1/4 cup and sauce is almost syrupy, stirring constantly, about 2 minutes. Reduce heat to low. Stir in tomato and cook 1 minute. Add 4 butter pieces 2 at a time, shaking and rotating skillet. Immediately pour sauce into small bowl. Stir in cilantro. Adjust seasonings. Spoon over grilled steaks.