Buffalo steaks with grilled mushroom and garlic gravy

For the steaks:
4 teaspoons soy sauce
2 teaspoons peanut oil
1 teaspoon freshly ground pepper
1 teaspoon cardamom
1/2 teaspoon onion powder
1/2 teaspoon paprika
4 buffalo strip steaks, about 10 ounces each
For the gravy:
2 portobello mushrooms, about 3 ounces each
4 tablespoons extra virgin olive oil, divided
1/2 teaspoon lemon-pepper seasoning
1/2 teaspoon salt, divided
2 tablespoons minced onion
6 to 8 cloves garlic, minced
1/8 teaspoon freshly ground pepper
1/2 cup red wine
1-1/2 cups brown gravy

1. To make the steaks: Combine all ingredients except steaks. Rub on both sides of the steaks, cover, and refrigerate for 2 to 4 hours.
2. Meanwhile, prepare the gravy: Rub the portobello mushrooms with 2 tablespoons of the olive oil, lemon-pepper seasoning, and 1/4 teaspoon of the salt. Grill the mushroom for 8-10 minutes over direct medium heat. Remove from grill, cut into small dice, and set aside.
3. Saute the minced onion and garlic in the remaining 2 tablespoons of the oil for 1 to 2 minutes; add the wine and reduce until wine is gone. Add the brown gravy and reserved mushroom. Stir to blend; simmer for 15 minutes, stirring occasionally.
4. For gas grills, increase heat to High. Grill steaks over Direct High heat for 8 to 12 minutes, turning once halfway through grilling time, or until desired doneness.