Grilled Mushroom Burgers with Tarragon Crema

For sauce, in a blender or small food processor combine soaked, drained cashews with the next four ingredients (through garlic). Cover and blend until smooth, gradually adding plant-based milk until sauce is creamy and spreading consistency. Stir in tarragon. Season with pepper. 2. Brush mushrooms with vinegar. Grill mushrooms over medium 15 to 20 minutes or until tender, turning once. 3. Fill buns with spinach, mushrooms, and tomato slices. Spoon sauce over top. Serve immediately.