Step 1

Process fish sauce, lime juice, sugar, garlic, chilli, green onion and coriander roots and stems until almost smooth. Place pork in a glass or ceramic dish; rub marinade all over pork. Cover; refrigerate for 6 hours or overnight.

Step 2

Preheat oven to 180°C.

Step 3

Remove pork from marinade; reserve marinade. Heat oil in a large flameproof roasting pan over medium-high heat. Cook pork until browned all over. Transfer pan to oven. Roast pork for 1½ hours or until cooked through. Remove pork from oven; rest, covered loosely, for 15 minutes.

Step 4

Meanwhile, place reserved marinade in a small saucepan over low heat. Simmer, stirring occasionally, for 15 minutes, or until reduced by half. Cool.

Step 5

Slice pork. Using a vegetable peeler, peel cucumbers into long thin ribbons.

Step 6

Place pork in lettuce cups with tomato, cucumber, bean sprouts and coriander leaves; drizzle with reduced marinade. Serve with lime cheeks.