Mix the mayo with the horseradish, paprika, salt, and black pepper. Set aside in the fridge until ready to use.
In a food processor, add the basil, walnuts, garlic, and olive oil. Pulse until the pesto is formed. Set aside in a bowl.
Use a julienne peeler or spiralizer to create the zucchini noodles.
Preheat a cast iron skillet, frying pan, or grill to medium high heat. Season the steaks liberally with salt and pepper. Cook the steaks to brown on all sides, reaching an internal temperature of 135 for medium rare. (or your desired doneness)
Allow to rest for 10 minutes while you prepare the zucchini.
Preheat a pan to high heat and add a little oil. Add the zucchini and cook for 1 minute, tossing in the pan as you cook. Add in the pesto and remove from heat. Toss the pesto with the zucchini and divide it onto the plates.
Top the zucchini with the steak, and drizzle on the sauce. Serve.