How to Make It
To prepare the chimichurri: In a blender or food processor, combine all ingredients and pulse on high until smooth and uniform.
To prepare the tacos: Heat a grill pan over high heat. Sprinkle salt, chili powder, and black pepper over both sides of steak. Spray grill pan with cooking spray and add steak to pan; cook on both sides until desired degree of doneness (about 4-5 minutes per side, for medium rare). Let sit for at least 10 minutes, slice steak against the grain.
In a large skillet coated with cooking spray, fry eggs until whites are set, about 3-4 minutes.
In a small skillet, warm tortillas one at a time. Top with fried eggs, steak, avocado, radishes, queso fresco, and chimichurri. Garnish with fresh cilantro and limes, if desired. Serve immediately.