CORN! Fill a large pot with water and heat to boiling. Boil corn for 6-10 minutes. Remove from water with tongs. Once cooled a bit, cut the corn off of the cob. Set aside.
MARINADE! While the water's heating, in a medium bowl mix together the marinade ingredients: lemon juice, clementine juice, olive oil, 1 of the minced garlic cloves, 1 T of the chopped cilantro, 3 t of the salt, and the tajin. Add meat and immerse in marinade. Let sit for 10 minutes.
CHIMICHURRI SAUCE! In a small bowl, combine: mayo, ½ cup of the lime juice, sherry vinegar, chopped parsley, the remaining ½ cup of the chopped cilantro, the remaining minced garlic clove, and 1 ½ t of the salt. Whisk briefly with a fork until well combined. Set aside.
SALAD! In a medium bowl, combine the corn salad ingredients: corn, black beans, tomatoes, the remaining 1 T of the lime juice, the remaining ½ t of the salt, and the black pepper. Slice the avocados and set aside.
MEAT! Heat a grill pan on med-high. Spray with cooking spray and use basting brush to spread the oil around, into the nooks. Cook skirt steak for 6 mins (or more), flipping frequently. Cut meat into strips, against the bias (cross-grain).
As a final step, sprinkle crumbled cotija over plated meal.