Marinate the pork shoulder slices in achiote paste, orange juice, pineapple juice, cumin, oregano, salt, and pepper. Refrigerate for at least 2 hours.
Preheat your grill or skillet over medium-high heat.
Grill the marinated pork slices for about 4-5 minutes per side until cooked through and slightly charred.
Remove the pork from the grill and let it rest for a few minutes.
Warm the corn tortillas on the grill for about 30 seconds on each side.
Thinly slice the cooked pork into bite-sized pieces.
Assemble each taco by placing a generous amount of pork on a tortilla.
Top with fresh cilantro, diced onion, and sliced radishes.
Serve with lime wedges on the side.