Place cleaned Portobello mushrooms in large plastic bag, add Mrs. Dash® Garlic Herb Marinade and marinate for 10 minutes. Combine 2 Tbsp. (30mL) Mrs. Dash® Garlic Herb Marinade, corn, green onions and plum tomatoes. Place mushrooms on preheated grill and cook until tender about 3-4 minutes per side. Brush with extra Mrs. Dash® Garlic Herb Marinade during grilling, if needed. Turn Portobello mushroom topside down, fill with salsa and serve.