Preheat a grill or grill pan to high heat.
Combine the smoked paprika, chili powder, ground cumin, 1/2 teaspoon kosher salt, and 1/2 teaspoon black pepper in a small bowl and rub evenly over both sides of the skirt steak.
Grill the steak to your desired doneness (about 3–5 minutes per side for medium-rare depending on thickness). Remove and let rest 5–10 minutes before slicing against the grain.
While the steak rests, peel the plantain and slice into 1/2-inch thick rounds.
Heat 2 tablespoons olive oil in a 12-inch skillet over medium-high heat until hot but not smoking.
Fry the plantain slices in the hot oil until golden brown on both sides, about 2–3 minutes per side. Transfer to a paper towel–lined plate to drain.
In a large salad bowl, add the chopped romaine, then top with avocado slices, halved cherry tomatoes, black beans, steamed corn, tortilla strips, crumbled cotija, and the fried plantains.
To make the dressing, add the packed cilantro, Greek yogurt, 2 tablespoons olive oil, garlic cloves, lime juice, lime zest, and 1/4 teaspoon kosher salt to a food processor or high-powered blender and puree until smooth and creamy.
Slice the rested steak thinly and arrange on top of the salad.
Drizzle the cilantro-lime dressing over the salad, toss gently if desired, and serve immediately.