Preheat the oven to 350 degrees F.
Chop the cooked flank steak to a fine dice. Saute chopped flank steak in a little oil for 1 to 2 minutes, or until heated through. Add cilantro and onion and cook for 5 minutes. Remove from heat. Combine the 1 cup of the monterey jack and 1 cup of the cheddar and mix well. Add cheese to steak mixture. Stir well and reserve, covered.
In another saute pan, heat oil over medium heat. Fry tortillas, one at a time, just until soft, about 10 seconds. Pat tortillas dry on paper towels. Portion out beef mixture evenly among the 16 tortillas and roll up. Place enchiladas on a baking sheet or in 1or 2 rectangular casserole dishes.
Cover enchiladas with cilantro cream sauce and top with remaining cheese. Bake for 6 to 8 minutes, or until cheese melts and sauce is bubbling.
Blanch cilantro in boiling water for 30 seconds and puree in blender with jalapeno. In a saucepan reduce heavy cream by half. Stir in cilantro-jalapeno puree and cumin. Adjust with salt and pepper.
Recipe courtesy of Michelle LeBleu, Houston Astros