Prepare and sauté spices: Slice garlic and shallots roughly, crush candlenuts, and slice galangal. Heat 1 tablespoon oil in a pan, add garlic, shallots, candlenuts, galangal, turmeric, and curly red chilies. Sauté on medium-low heat until fragrant and slightly brown.
Blend spices: Let the sautéed spices cool slightly, then blend with 80 ml water until smooth to release flavors.
Prepare other ingredients: Slice tomato into large pieces, slice spring onions, lime leaves, and cayenne peppers. Prepare basil leaves generously.
Prepare chicken and mix marinade: Slice chicken breast thinly lengthwise. In a bowl, combine chicken with salt, mushroom stock powder, sugar, pepper, blended spices, coconut milk, egg white, and cornstarch. Mix well to coat evenly.
Add complementary ingredients: Add sliced cayenne peppers, lime leaves, tomato, spring onions, and basil leaves to the chicken mixture. Stir to combine.
Wrap and steam: Prepare banana leaves by placing sliced lemongrass and bay leaves underneath. Place the chicken mixture on top, wrap tightly using banana leaves secured with toothpicks. Steam the wrapped chicken for 25-30 minutes. Adjust steaming time if stacking chicken higher.
Optional freezing: Cool the steamed pepes completely. Wrap each portion tightly with plastic wrap to preserve aroma and prevent freezer burn before freezing.
Serve: Reheat steamed chicken pepes before serving. Serve with steamed white rice.