Slow cooker Thai green chicken curry

Name: Slow cooker Thai green chicken curry
Ingredients: 6 chicken thighs, skin removed and boneless, cut into 4–5cm/1½–2in chunks; 6 tsp Thai green curry paste; 400ml tin coconut milk, light or full-fat; 2 tsp brown sugar, plus extra to serve (optional); 2 tsp fish sauce, plus extra to serve (optional); 300g/10½oz sweet potatoes (about 1 large one), peeled and cut into 2cm/¾in chunks; 100g/3½oz frozen edamame beans; 5 spring onions, trimmed and cut into 3–4cm/1¼–1½in chunks; 2 tsp cornflour (optional); salt and freshly ground black pepper; 2 limes, 1 juice only and 1 cut into wedges; freshly cooked sticky or jasmine rice, to serve