Heat the oil in a large skillet set over medium-high heat. Coat the chicken in the cornstarch, then brown on all sides. Place chicken, potatoes, onion, tomatoes, coconut milk, stock and curry powder in a slow cooker and stir to combine. Cover and cook on low for 9 to 10 hours. When ready to serve, season with salt and pepper and stir in the blanched snow or snaps peas, they will heat through in 1 to 2 minutes
Note: This recipe is designed for an oval-shaped slow cooker with a 5 litre or more capacity. To blanch snow or snap peas, plunge into boiling water for 30 seconds. Cool in cold water and drain well.