Bring steaks to room temperature and season meat liberally with Kosher salt and coarse black pepper. Preheat a large, cast-iron skillet or griddle to medium-high.
Preheat oven to 450°F.
In a skillet or medium saucepot, melt 2 tablespoons butter over medium heat and add onions, garlic, salt, pepper, pimentón and bay. Cook the onions until very soft, about 15-20 minutes, stirring occasionally. Add sugar, vinegar, Worcestershire, mustard, 1/2 cup chicken stock and the tomato sauce. Bring onions to a boil then reduce heat to simmer.
Place potatoes in a pot and cover with water. Bring to a boil, salt the potatoes and cook to tender; drain and put back in hot pot. Add remaining 1/2 cup chicken stock, cheese and remaining 2 tablespoons butter. Mash to desired consistency and season with salt and pepper to taste. Cover to keep warm.
Place the beans and shallots on a baking sheet and drizzle with olive oil. Season with salt, pepper then sprinkle the red peppadews or pimientos over the beans. Roast the green beans to tender-crisp and brown at edges, 15 minutes.
Drizzle steaks with a little olive oil then cook in the hot pan for 8-10 minutes for medium-rare. Cool the steaks then slice 1/4-inch thick against the grain.
Fan the sliced steak on plates and top with some barbecued onions. Serve mashed potatoes and green beans alongside.
Tournedos with Creamed Spinach
Roasted Green Beans and Tomatoes