Vegan Portobello Stroganoff

Name: Vegan Portobello Stroganoff
Ingredients: 8 ounces vegan sour cream (such as Tofutti®); 1/2 cup water; 3 tablespoons dried minced onion; 2 tablespoons all-purpose flour; 2 teaspoons vegan no-beef bouillon; 1/4 teaspoon garlic powder; 1/4 teaspoon dried basil; 1/4 teaspoon ground black pepper; 1/2 cup dry red wine; 1 tablespoon olive oil; 2 tablespoons soy sauce; 1 tablespoon balsamic vinegar; 2 cloves garlic, minced; 2 large portobello mushroom caps, stems and gills removed; cooking spray; 1/4 cup water, or as needed (optional)