Place 1/2 chopped onion, 2 cloves garlic, parsley, oregano, paprika, anise seed, black pepper, cumin, sage, thyme, bay leaves, cloves, soy sauce, vinegar, orange juice, and lime juice in a blender; pulse until a very well-blended paste is achieved, scraping down sides as needed, 3 to 5 minutes. Spread paste on both sides of the flank steak. Wrap steak in plastic and refrigerate at least 6 hours to overnight.
Preheat an outdoor grill for medium-high heat and lightly oil the grate. Remove excess marinade from flank steak.
Grill steak until it begins to firm and is hot and slightly pink in the center, about 8 minutes per side. An instant-read thermometer inserted into the center should read 140 degrees F (60 degrees C). Chop steak into small pieces and transfer to a platter; cover and keep warm until ready to serve.
Place 1 chopped onion, tomatoes, chipotle peppers, and 3 cloves garlic in a blend; pulse until desired consistency. Add water if the salsa becomes too thick. Transfer salsa to a bowl.
Heat tortillas in a microwave safe plate until warm, about 1 minute.
Serve beef over stacks of two corn tortillas with salsa and sprinkle with remaining 1/2 chopped onion, radishes, and cilantro.
You can tinker with this recipe to make the marinade as strong or as weak as you wish. You can double up or cut the marinade ingredients in half or increase the amount of any particular herb or spice. I find that the flavor of the meat in this recipe is almost addicting and I always end up grilling about ten pounds of beef so I make extra marinade. The longer you marinade the meat, the better.
You may also use pork loin or pork chops. This recipe works really well with almost any variety or cut of meat. Thinly cut steaks work best with the tacos.