Season the flank steak generously on all sides with kosher salt and freshly ground black pepper, then place it in a shallow baking dish. Sprinkle the finely chopped garlic over the steak, squeeze the juice from both limes over everything, and pour the beer on top. Cover the dish and let the steak marinate in the refrigerator for at least 1 hour or up to 4 hours for deeper flavor.

Combine masa harina and 1 teaspoon kosher salt in a large bowl. Add 1 1/2 cups hot water and mix with a wooden spoon. Once combined, knead the mixture with your hands until it forms a dough. If the dough feels crumbly or dry, add additional hot water a little at a time until the dough is pliable but not sticky. It should not crack when rolled into a ball.

Heat a dry comal, cast iron skillet, or nonstick frying pan over medium-high heat. Break off a pool-ball sized piece of masa dough and roll into a ball. Flatten it into a 1/2-inch thick circle. Place the dough onto the hot pan and cook undisturbed for about 2 minutes until a crust forms; reduce heat if it cooks too quickly or burns. Flip and cook for another 2 minutes. Remove from the pan and carefully pinch the edges to create a rim, then flatten the center to form a base. Repeat with remaining dough. I like to oil the pan lightly for a crisper bottom on the sopes.

Preheat a grill to medium-high heat (or heat a skillet with a slick of oil if using stovetop). Remove the marinated steak from Step 1 from the marinade, letting excess marinade drip off. Grill the steak for about 10 minutes, turning once, until it reaches your preferred doneness (about medium). Let it rest for 5 minutes after grilling, then slice thinly across the grain into bite-sized pieces. I always allow a little resting time for the meat to keep it juicy.

Place the sopes from Step 3 back onto a hot comal or skillet over medium-high heat. If you like a crisper base, add a small amount of oil to the pan before reheating. Warm them through until hot and lightly crisped.

To assemble, top each warm sope with a few slices of grilled steak from Step 4. Add avocado slices, thinly cut watermelon radishes, sliced red onion, and a sprinkling of crumbled queso fresco cheese. For an extra touch, I like to finish with a drizzle of good olive oil and a squeeze of lime juice over the top.