Cut the potatoes into bite-size chunks (halve, then halve again). Steam in a rice cooker or electric steamer until a fork slides in easily, about 15 minutes. Shake off any pooled water before frying so the potatoes aren't soggy.

Tear the king oyster mushroom into rough chunks about the same size as the potatoes — tearing, not cutting, gives a meaty, fibrous texture. Separate the bunapi mushroom stems and pick the Thai basil leaves off their stems.

Melt 1 tablespoon of butter with a splash of cooking oil in a wide pan over medium-low heat — the oil stops the butter from burning. Add the steamed potatoes in a single layer and fry, turning occasionally, until golden and crispy on all sides, about 5 minutes. Scoop out to a plate and set aside.

Add the small piece of butter to the same pan and tip in all the mushrooms. Fry until browned and fragrant, about 2 minutes — the deeper the color, the richer the aroma. Return the crispy potatoes to the pan.

Season with salt, white pepper, black pepper, curry powder, and oregano; toss until every piece is coated. Add the Thai basil and stir-fry over high heat until the leaves just soften, about 30 seconds. Serve immediately — best hot and crispy.