Slice the Tempeh: Thinly slice the tempeh.
Prepare the Spices: In a mortar and pestle, add garlic, coriander, and salt. Mash until smooth.
Mix the Batter: In a bowl, mix flour, rice flour, mashed spices, turmeric powder, mushroom bouillon, sugar, pepper, baking powder, egg, and water. Stir well.
Add Green Onions: Slice green onions and add to the batter. Stir well.
Fry the Tempeh: Dip tempeh into the batter, then fry over high heat for a few moments. Drain.
Prepare Sweet Soy Sambal: In a mortar and pestle, add garlic, green Thai chili, red Thai chili, salt, and MSG. Mash coarsely, then transfer to a bowl. Add sweet soy sauce, kaffir lime juice, and fried shallots. Stir well.
Serve: Mendoan is ready to serve.