How to Make It
Preheat oven to 400°F. Starting about 1/4-inch from stem, split jalapeños lengthwise, keeping halves intact near stem. Remove seeds with a spoon, and discard. Place jalapeños in a single layer on an aluminum foil-lined baking sheet. Bake in preheated oven until slightly tender, about 15 minutes.
Heat a medium non stick skillet over medium. Add beef, taco sauce, and taco seasoning to hot skillet, and cook, stirring occasionally, until beef is cooked through, 7 to 8 minutes. Reduce heat to low, and stir in cream cheese and colby-Jack. Cook, stirring often, until cheese is melted, about 2 minutes. Remove from heat.
Pour oil to a depth of 3 inches into a large Dutch oven; heat over medium to 350°F.
Fill each jalapeño with about 1/2 tablespoon of the beef mixture (or enough to fill jalapeño); secure ends together with a wooden pick.
Stir together cornmeal, flour, kosher salt, and baking powder in a medium bowl. Stir together buttermilk, whole milk, and egg in a small bowl. Whisk buttermilk mixture into cornmeal mixture until just combined.
Submerge 5 or 6 filled jalapeños in cornmeal mixture, and carefully place in hot oil. Fry jalapeños until golden brown, 5 to 7 minutes. (Adjust heat to maintain 350°F while frying.) Place on a wire rack, and immediately sprinkle with coarse salt. Repeat with remaining filled jalapeños. Serve with Lime-and-Cilantro Crema.