Preheat oven to 400ºF. Peel onions, leaving the root on and cut onion into rings about ¼-inch thick and place in a bowl with buttermilk and a pinch of salt and pepper. Toss onion rings in the buttermilk until they are well coated and let sit for a few minutes.
Season each of the steaks with ½ teaspoon of salt and ¼ teaspoon of pepper. Heat a large skillet on high with 1 tablespoon of canola oil. After one minute of heating, gently add the steaks to the pan. Sear them for 3-4 minutes on each side so they develop a nice sear. Place in oven for 5-6 minutes or until internal temperature of the steaks reaches a minimum of 145ºF.
Pour 3-4 cups of canola oil into a large pot (there should be several inches of extra room at the top of the pot) and heat to 365ºF. Meanwhile, strain the excess buttermilk off the onions in a colander. Pour half of the flour on a sheet tray and toss onions in the flour. Once fully coated, sprinkle the rest of the flour on top of the onions until they are well coated and not gummy. Place ¼ of the onions gently in the heated oil and cook for 3-4 minutes, moving them around with tongs. Remove when slightly golden brown, drain on a paper towel-lined plate and season with salt and pepper. Repeat with the rest of the onions.
Toss arugula with red wine vinaigrette a pinch of salt and pepper, and top with blue cheese crumbles. Serve steak with arugula salad and onion strings.
Approximate Nutritional Information (Per serving):
Calories 1040, Fat 52g, Sat. Fat 18, Trans Fat 0g, Cholesterol 205mg, Sodium 870mg, Total Carbohydrate 60g, Fiber 3g, Sugars 8g, Protein 77g
ALLERGEN INFORMATION: Tree Nut Free, Peanut Free, Egg Free, Soy Free