Combine red curry paste, brown sugar, garlic, cilantro, red pepper, onion, ginger, and red chili in a food processor or blender, and process until a paste forms.
Add the paste to the slow cooker and stir in coconut milk and chicken stock. Add the chicken to the slow cooker, cover and cook on high for 4 hours, or low for 8 hours.
Add in the peas and rice noodles and cook for ½ hour longer. Stir in lime zest, lime juice and fish sauce and season to taste with salt.
Serve in bowls topped with cilantro, green onions, additional red chiles and lime wedges.