Step 1

Combine oyster sauce, sesame oil, fish sauce and lime juice in a bowl. Toss prawns with half the sauce in a separate bowl. Heat olive oil in a large frypan over high heat. Cook prawns, turning, for 4 minutes or until charred and just cooked.

Step 2

Meanwhile, soften noodles in a bowl of boiling water for 1 minute, then drain.

Step 3

Divide the noodles, prawns and choy sum among bowls, drizzle with remaining sauce and serve with chilli and peanuts.