In a large skillet over medium-high heat, heat oil. Add onion, garlic, and jalapeno and cook until onion is soft, 5 minutes. Add enchilada sauce and cook until slightly thickened, about 8 minutes.
In a medium bowl, combine turkey, pinto beans, and 2 cups Monterey jack. Add 1 cup enchilada sauce mixture and 3/4 cup sour cream and toss to combine, then season with salt.
Place 1 1/4 cups enchilada sauce in a 9"-x-13" baking dish and spread evenly across the bottom. Add a small scoop of the turkey mixture in the center of a tortilla, then roll up and place seam side down in the dish of enchilada sauce. Repeat with remaining tortillas. Spread remaining enchilada sauce on top and sprinkle with remaining 1/2 cup Monterey jack.
Bake until cheese is bubbling and melty, 15 to 20 minutes.