1For spice mixture:
Mix all ingredients in small bowl. (Can be made 1 week ahead. Store airtight at room temperature.)
Whisk oil, vinegar and mustard in large bowl to blend. Season with salt and pepper. Add greens, bell pepper and onion and toss to coat. Divide salad between 2 plates.
3Spread spice mixture on plate. Coat both sides of steaks with spice mixture. Dip both sides of steaks into melted butter. Heat heavy large skillet over high heat until very hot. Add steaks and cook to desired doneness, about 2 minutes per side for medium-rare. Transfer to cutting board; let stand 2 minutes. Thinly slice steaks crosswise. Arrange slices atop salads. Sprinkle with cheese. Garnish with tomato and serve.