1.Mash steam yam whist hot and toss with its seasoning and set aside.
2.Boil chick peas with 1 bowl of water in low heat until cooked；chop coarsely.
3.Blend mushroom stem in blender, squeeze out water and marinate with ½tsp salt and 1 tsp sugar
for 20 minutes.
4.Heat 3 tbsp oil in wok, sauté mushroom stem until fragrant, add in all ingredients D and stir-fry briefly, dish out and mixes with mashed yam and chick peas. Apportion the mixture into 8 equalportion, make like burger patties and coat with some corn flour, sear in hot oil until both sides turns golden brown.
5.Halve buns and spread with butter, sear in pan until golden brown, and then spread with ingredients B, top with lettuce，vegetarian burger, tomato and capsium slices , done.