Step 1
Sprinkle sazon seasoning over pork cubes and toss to coat evenly. Transfer to a large zip-top plastic bag. Mix orange juice lemon juice lime juice cumin paprika chili powder coriander salt and pepper together in a mixing bowl. Pour into plastic bag with pork; gently squeeze to evenly distribute marinade. Seal bag and place on a plate. Refrigerate 8 hours or overnight.
Step 2
Remove pork from marinade; reserve marinade. Heat oil in large skillet or Dutch oven over medium-high heat. Cook and stir pork until brown on all sides 3 to 5 minutes. Add reserved marinade and enough chicken stock to barely cover the pork. Bring to a boil over high heat; cover reduce heat to low and simmer 30 minutes. Remove lid and continue to simmer until meat is falling-apart tender about 45 minutes.
Step 3
Transfer pork with a slotted spoon to a bowl; reserve 1/3 cup of cooking liquid. Cool pork slightly; shred pork with two forks. Mix in reserved cooking liquid cilantro and 7 ounces of crumbled queso fresco cheese.
Step 4
Bring a large pot of lightly salted water to a boil. Cook pasta shells in the boiling water stirring occasionally until tender yet firm to the bite about 13 minutes. Drain.
Step 5
Preheat oven to 350 degrees F (175 degrees C).
Step 6
Cover the bottom of a 9x13-inch baking dish with 2 cups of pasta sauce. Stuff shells with a spoonful of pork mixture and arrange in baking dish. Pour remaining pasta sauce evenly over stuffed shells and sprinkle with remaining crumbled queso fresco.
Step 7
Cover with aluminum foil and bake in preheated oven until hot and bubbly about 30 minutes. Let stand 10 minutes before serving.