Combine 1/2 of the grated garlic, all of the dried oregano, 2 teaspoons salt and the pepper into a paste.
Score the trimmed roast with a knife point and rub the paste into the roast, then place roast in a gallon freezer bag or other dish/container that will fit in the refrigerator.
Pour juice of 3 oranges, juice of 3 limes, the red wine, and 2 teaspoons of the lite olive oil over the roast, seal bag and turn the bag several times to combine the ingredients.
Place in refrigerator for at least 3 hours, or the day before you plan to serve.
Heat oven to 350°F.
Place roast and marinade in a roasting pan, cover with foil, and roast until the meat falls apart when pulled with a fork, 3 to 4 hours, up to 6 depending on the cut- it must become fork tender.
Remove roast from oven and let it rest for 20 minutes, then pull roast into shreds with a fork, leaving the meat in the pan juices- it's ready to serve.
Prepare Mojo Criollo: put onion slices in a bowl deep enough for the onions to be covered with the juice (I use a 2-cup glass measuring cup).
Put the rest of the fresh grated garlic, 1 teaspoon kosher salt, juice of 3 limes and juice of 5 oranges and the optional juice of 2 blood oranges over the onions, press down to make sure onions are submerged in the juice.
Allow the onions to marinate in this mixture for at least 20 minutes (important step).
Heat 1/4 cup of the lite olive oil in a skillet.
Quickly and carefully, pour the onions and all the juices into the hot oil and stir fry for about 2 to 3 minutes, just to soften the onions.
Pour the Mojo into a serving dish and serve with the roast on the side.