Marinated Flank Steak

Ingredients

• 1 flank steak, 2 to 2 1/2 pounds, trimmed
• Marinade:
• 1 large shallot, minced
• 2 garlic cloves, minced
• 3 tablespoons soy sauce
• 3 tablespoons olive oil
• 1 tablespoon finely chopped fresh thyme or 1 teaspoon dried
• Seasoning salt
• Freshly ground black pepper
• Sauce:
• 1/4 cup sour cream or crème fraiche
• 2 teaspoons cream style prepared horseradish
• Salt and white pepper
• 1 tablespoon chopped chives or scallions