Place the flank steak under a sheet of plastic or zip top bag. Pound thin with the flat side of a meat mallet until about 1/2” thick all the way across.
Combine the marinade ingredients in a pitcher. Blend or process with an immersion blender. Transfer to a large bag or brining container.
Place the thin pounded flank steak to the marinade. Seal and let marinate 2-10 hours.
Fill two chimney starters full of lump charcoal and light fire starters underneath. Place the chimneys inside the Yoder Smokers Adjustable Flat-Top Charcoal Grill. Place a GrillGrate panel over the top of one chimney and place the tomatillos and jalapeños on top. Let them char, removing the tomatillos when softened and breaking open and the jalapeños until blackened on the surface. Transfer to a bowl and cover with plastic wrap to steam. Peel the skin from the jalapeños and remove the seeds.
When the charcoal is burning hot to the top of the chimneys, dump and move grate into place.
While the jalapeños steam, make the pico de Gallo. Combine all ingredients in a bowl and mix well. Store in the refrigerator for up to one week.
To make the avocado salsa. Combine all ingredients in the blender and blend until smooth. Thin with water to desired consistency.
Remove the flank steak from the marinade and transfer directly to the grill, over the hot charcoal. Grill to char the surface, then flip and repeat. Remove from the grill when over 130ºF internal temperature and well browned. Rest before dicing.
Dice the flank steak into small pieces. Toss in the juices gathered on the board and season with more Cattleman’s Grill Mexicano Seasoning.
Warm the Caramelo tortillas on the grill until lightly charred and slightly crispy, but still pliable.
To build the tacos, fill the tortillas with the chopped flank steak. Top with the pico de Gallo and avocado salsa. Sprinkle with cotija cheese and lime juice, to taste.