PREP: Preheat the grill to 450 degrees F. Once heated, clean the grill grates with a wire brush. Liberally oil the grill (I do this by drenching a paper towel in canola or vegetable oil and, holding tongs, rubbing the paper towel over the grill).
CORN: Shuck corn and discard silk. Drizzle corn with olive oil and lightly sprinkle with salt and pepper. Rub the oil and salt/pepper into all sides of the corn. Add the corn to the heated and oiled grill over direct heat. Grill corn about 10-12 minutes total, rotating every 3-4 minutes until bright in color and lightly charred. Let grilled corn cool before cutting it off the cob.
STEAK: Prepare the rub by mixing together the garlic powder, ground coriander, cumin, paprika, chili powder, salt, pepper, and brown sugar. Remove the flank steak from packaging and blot dry with a paper towel. Drizzle 1 tablespoon oil on the top of the steak. Sprinkle half the rub on top and gently press in. Flip the steak over. Drizzle remaining 1 tablespoon oil on the bottom of the steak and sprinkle on the remaining rub mixture. Gently press in. Place the spiced-rubbed steak directly on the grill and cook for 4-5 minutes per side, or until the internal temperature is 130-135 degrees F for medium rare or 145 degrees for medium. (I use a meat thermometer here. My grill takes exactly 4 minutes per side at 450 degrees F.) Remove the steak from the grill to a cutting board. Tent with foil and allow to rest for 5-10 minutes. Once the steak has rested, slice it very thinly against the grain (See Note 1).
SALSA: While the steak cooks, prepare the salsa. Slice the cooled corn off the cob and add to a large bowl. Dice the veggies -- the avocados, red onion, red pepper and cilantro and add to the corn. Add 1 tablespoon olive oil, 1/4 cup lime juice, 1 teaspoon cumin, minced jalapeno, minced garlic, and, if desired, crushed red pepper flakes to the veggies. Gently toss together. Add salt and pepper to taste (I add 1/4 teaspoon of each). Toss again and serve over steak. If desired, drizzle everything with 1 more tablespoon olive oil. Serve with extra cilantro and lime wedges if desired.
Video
Notes
Note 1: Slicing the steak: Find the fibers on the steak and determine how they are running along the steak. Once you find that grain, slice perpendicular (here's a visual). This will keep the meat juicier and much more tender. It's easier to chew when cut against the grain.