Pound the steak to ½-inch thickness for even cooking and tenderness. Pat the steak dry and season generously with salt and pepper. Heat 2 tablespoons of olive oil in a deep skillet or braiser over medium-high heat. Sear the steak for 3–4 minutes per side until a deep golden crust forms. Remove from the pan and set aside.
In the same pan, lower the heat to medium and add the onion, red bell pepper, and mushrooms. Sauté for 5–6 minutes, stirring occasionally, until softened and slightly caramelized.
Stir in the garlic, red pepper flakes, oregano, and basil, cooking for 30 seconds until fragrant.
Pour in the red wine and scrape up any browned bits from the pan. Let it simmer for 1 minute.
Stir in the crushed tomatoes, beef broth, and sugar (if using). Bring to a gentle simmer.
Return the steak to the pan, nestling it into the sauce. Spoon some sauce over the top. Cover and simmer on low heat for 45–60 minutes, or until the steak is fork-tender. If the sauce thickens too much, add a splash of water or broth. If it’s too thin, uncover and simmer for a few minutes to reduce.
Once the steak is tender, remove from heat and let rest for 5 minutes. Garnish with fresh basil and, if desired, a sprinkle of grated Parmesan.
Serve with crusty bread, pasta, or over creamy polenta to soak up that rich sauce.