Fries: Heat oil in a deep fryer or large pot. Cook the McCain Shoestring Fries according to the package instructions until crispy. Season with salt and set aside.
Steak: Season the steak with salt and pepper. In a large non-stick pan, heat the oil and then add butter. Once the butter begins to sizzle, add the garlic, thyme, and steak. Cook the steak for approximately 4 – 6 minutes on each side for medium rare, or until it reaches your desired doneness. Let the steak rest before thinly slicing.
Chimichurri: Combine all chimichurri ingredients in a blender and blend until smooth. Season with salt to taste.
Pickled Onions: Soak the sliced onions in boiling water for 5 minutes, then drain. Mix the onions with red wine vinegar, olive oil, sumac, and a pinch of salt.
Assembly: Spread chimichurri on each bun, followed by slices of steak, pickled onions, and a handful of rocket. Serve with a side of McCain Shoestring Fries.