Snap the stem end of each bean and pull the string down the side (repeat on the other edge if the fiber is tough). Line up 4-5 beans flat on the board and slice them diagonally into short lengths — the angle gives more surface for the sauce to cling to. Set aside.

Chop the wood ear very fine. Tear the king oyster into strips, then chop into a fine springy mince. Slice the shiitake and cut across into a fine mince, and mince the white beech mushrooms the same way after separating them with your fingers. Keep all the mushrooms together in one bowl.

Heat a generous pour of oil in the wok over medium-high heat so the beans are half-submerged. Add the beans and fry 2-3 minutes, turning so they blister evenly — wrinkled and slightly darker at the edges, still firm and bright green inside. Lift out and drain. They are cooked but unseasoned.

Pour off most of the oil, leaving about a tablespoon. Add the king oyster, shiitake, white beech and wood ear all at once. Spread into a single layer and leave undisturbed for about 2 minutes until the undersides turn golden, then toss and fry another minute until the moisture has cooked off and the mince smells fragrant. Add the soy sauce, vegetarian oyster sauce, five-spice, white pepper and sugar; toss quickly for 30 seconds.

Return the drained beans to the wok over high heat, sprinkle over the salt and toss continuously for 30-60 seconds so every bean is coated in the glossy mince. Taste for seasoning, kill the heat and plate immediately. Serve hot with steamed white rice.