1. Sprinkle chicken breasts with salt and pepper. Working in batches, cook 2 breasts in hot olive oil in a Dutch oven over medium-high heat 4 to 5 minutes on each side or until browned. Remove chicken from Dutch oven; cover with aluminum foil to keep warm.
2. Add onion and bell pepper to Dutch oven; sauté 5 minutes or until tender. Stir in garlic and paprika; sauté 1 minute. Add mushrooms; sauté 5 minutes. Stir in tomatoes and tomato paste, and cook, stirring constantly, 2 minutes. Add flour, and cook, stirring constantly, 1 minute. Stir in broth; boil. Reduce heat to medium; simmer, stirring occasionally, 5 minutes. Stir in lemon juice, horseradish, and chicken; simmer 10 minutes or until chicken is cooked through. Add salt and pepper to taste.