Mix Vinasamex vegan marinade with garlic, Chinese five spice powder, white pepper, sugar, Shaoxing cooking wine, and sunflower oil to make a marinade.
Rub the portobello mushrooms thoroughly with the marinade on all sides and let them marinate for at least 30 minutes.
Heat a grill or frying pan over medium heat with some sunflower oil and fry the portobello mushrooms for 2 to 3 minutes on each side. Keep the heat low to prevent the spice mixture from burning. Reserve any leftover marinade!
Once all the portobello mushrooms are cooked, slice them into desired thick strips and transfer them to a plate or serving dish.
In the same grill or frying pan where you cooked the portobello mushrooms, fry the remaining marinade along with the spring onions and some extra sunflower oil for 1.5 minutes. Distribute the spring onion mixture over the portobello mushrooms and serve the dish.