First, mix together the minced garlic, ground cumin, achiote powder, salt, and pepper in a bowl.
Marinate the meat by rubbing the mixture all over the inside and outside of the deboned pig. Let it marinate for at least 2 hours, or overnight in the refrigerator.
Cook the rice according to package instructions.
In a large bowl, mix together the cooked rice, peas, and the chopped carrots, potatoes, and onions to use as stuffing.
Season the stuffing with salt and pepper to taste.
Stuff the pig with the rice mixture, packing it tightly to fill the cavity.
Sew or use kitchen twine to close the opening securely.
Preheat your oven to 350°F.
Place the stuffed pig on a roasting pan or in a large baking dish.
Roast the pig in the preheated oven for about 8 hours, or until the skin is crispy and the meat is cooked through. Baste the pig occasionally with its own juices or with a mixture of oil and water to keep it moist.
Once cooked, remove the pig from the oven and let it rest for about 15-20 minutes before serving.
Serve the Lechona hot, slicing it into portions along with the stuffing.