For the steaks: In a small bowl, combine the cumin, paprika, garlic powder, salt and pepper. Sprinkle over both sides of each steak and rub into the meat. Rest at room temperature for 2 hours.
Once the steaks have rested, heat a large cast-iron skillet or griddle pan on medium-high heat. Drizzle the steaks with olive oil on both sides, then add the steaks to the hot skillet. Cook for 3 to 4 minutes, then flip and cook on the second side just 2 minutes more, or until desired doneness. Remove the steaks to a plate, cover with aluminum foil and let rest for 10 minutes.
For the cucumber salad: In a medium bowl, combine the lime juice, vinegar, sugar, a pinch of salt and a few grinds of black pepper and whisk together until the sugar and salt have dissolved. Add the cucumber, radishes, red onion and jalapeno if using. Toss and let sit at room temperature while the steaks are resting. Serve the steaks topped with the cucumber mixture.