To prepare salad dressing, combine ranch dressing and horseradish in a small bowl; cover and chill.
To prepare steaks, combine black pepper, ground coffee, ground cumin, and ancho chile powder. Rub both sides of steaks with pepper mixture, and let stand 10 minutes.
Heat a nonstick grill pan over medium heat. Coat steaks with cooking spray. Add steaks to pan; cook 3 minutes on each side or until desired degree of doneness. Remove steaks from pan; let stand 7 minutes.
Combine shallots, fresh basil, bell peppers, juice, and tomatoes in a small bowl; toss well.
Arrange 1 cup arugula on each of 6 serving plates, and top each serving with 2 toast slices. Cut each steak diagonally across grain into thin slices. Divide steak slices evenly among the toast slices; top each serving with about 2 tablespoons tomato mixture. Drizzle each serving with about 1 tablespoon of the salad dressing. Serve immediately.