Heat a large nonstick skillet over medium-high heat; spray lightly with cooking spray. Sauté mushrooms and onion with salt in skillet until dark golden-brown and liquid fully evaporates (about 8 min.). Add garlic; cook 1 min. Remove mixture from heat and cool to room temperature. Whisk together marinade and green onions in a small mixing bowl. In a large mixing bowl, whisk together 1/2 cup marinade mixture, breadcrumbs and egg; mix in pork and cooled mushroom mixture. Using damp hands, shape into 16 evenly sized meatballs. Bake on a parchment paper-lined baking sheet in a preheated 400° oven until done (about 20 min.). Remove from oven and let stand 5 min. Heat a large skillet over medium-high heat; add cooked meatballs and remaining sauce to the pan. Cook and stir until sauce thickens and glazes the meatballs (2-3 min.). Serve immediately, garnished with green onions and sesame seeds.