Rinse the rice until the water runs clear. Put in a small saucepan with 250ml (1 cup) water, cover and bring to a simmer over medium heat. Reduce the heat to low and cook for 12 mins or until tender and the water is absorbed. Turn off the heat and stand, covered, for at least 5 mins.
Step 2 — Prep pickle, lime leaves
Meanwhile, very thinly slice the onion. Put the onion, 2 tsp white vinegar and ¼ tsp sugar in a bowl. Season with salt and pepper and toss to coat. Set aside to pickle, tossing occasionally, until needed. Separate the lime leaves, remove the central vein and finely shred (see cooking tip).
Step 3 — Cook mushroom 'meat'
Heat 2 tsp oil in a medium deep frypan over medium-high heat. Cook the mushroom meat and curry paste, breaking up the lumps with a spoon, for 2 mins or until the mushroom meat is browned. Stir in the lime leaves, coconut milk and 125ml (½ cup) hot water and bring to a simmer. Cover, reduce the heat to low and cook for 6 mins.
Step 4 — Cook vegetables
While the mushroom meat is cooking, thinly slice the zucchini on an angle. Trim the beans. Stir the zucchini and beans into the mushroom meat mixture and cook, covered, for 3-4 mins until the beans are tender.
Step 5 — Prep peanuts
Finely chop the peanuts.
Step 6 — Season curry and serve
Stir 1 tsp sugar and 1 tsp of the onion pickling liquid into the curry. Taste, then season with salt. Fluff the rice with a fork. Divide the rice, curry and pickled onion among bowls. Scatter with the peanuts to serve.