She juiced 4 large oranges and added a little bit of lime juice to end up with a pint of liquid.
Then she chopped a white onion and sweated it in a tbsp of oil. Then added two chopped garlic cloves and 1/2 brick of Achiote Paste. She then added the orange-lime juice plus 1/2 up non-sweetened pineapple juice and brought to a boil. Removed from the heat and cooled. Then ran it all through a blender.
The marinade is done.
Another recipe from the Yacatan, This from Rick Bayless - Mexico one plate at a time:
5 tablespoons(about 2 ounces) achiote seeds 1 1/2 tablespoons dried oregano, preferably Mexican
1 1/2 tablespoons black pepper, preferably whole peppercorns
1 1/4 teaspoons cumin, preferably whole seeds
1/2 teaspoon cloves, preferably whole
1 1/2 tablespoons cinnamon, preferably Mexican canela, that’s freshly ground or still in stick form (you’ll need about 6 inches of 1/2-inch diameter cinnamon stick)
Salt
14 large garlic cloves, peeled and roughly chopped
1 1/2 cups fresh sour orange juice
OR 1 cup fresh lime juice plus 1/2 cup fresh orange juice
1. The achiote marinade. Measure the achiote seeds and oregano into a spice grinder, adding the black pepper, cumin, cloves and cinnamon, and run the grinder until everything’s as powdery as you can get it (you may need to work in batches).
In a blender, combine the ground mixture with 1 tablespoon salt, the garlic and sour orange juice (or lime juice plus orange juice). Blend until smooth—there should be very little grittiness when a little is rubbed between your fingers.
If you’re working ahead, pour the mixture into a non-aluminum container, cover, refrigerate 6 hours or longer. Before using, blend the mixture again to give it an even smoother texture. (The long steeping and second blending isn’t absolutely essential, though without it the marinade may be a little gritty.)
2. Marinating the meat. In a large bowl or large plastic food bag combine meat and marinade, turning the meat to coat it evenly. (Though achiote has tenacious coloring properties, I suggest you do this quickly with your hands.) For the greatest penetration of flavor, let the meat marinate refrigerated (covered if in a bowl) for several hours, or even overnight.
Are either of these two close to what you were describing the Tablitas Marinade to be? These are "pork" marinades but I don't see why you couldn't use them on cross cut beef ribs.