Finely chop mushrooms by hand or alternatively, pulse in a food processor to finely chop.
Heat 1 tbs oil in a large non-stick frying pan over high heat. Add mushrooms and cook, stirring often, for 8 minutes or until all moisture has evaporated. Set aside to cool for 10 minutes. Drain any excess moisture and transfer mushrooms to a bowl. Wipe pan clean.
Clean and cut two roots from coriander. Place roots into a food processor, add green onions and 1 cup coriander leaves. Pulse until finely chopped. Add coriander mixture, mince, curry paste, egg and breadcrumbs to mushrooms Mix until well combined. Shape 1 tbs of mixture into balls with damp hands. Place onto a tray, cover and refrigerate for 1 hour if time permits (this helps hold meatballs together when cooking).
Heat remaining oil in a large non-stick frying pan over medium heat. Cook meatballs, in batches, shaking pan often, for 8-10 minutes or until just cooked through. Serve with lettuce leaves, sweet chilli sauce and lime wedges.