In a large saucepan melt 40g of the butter then saute the onions until soft. Season the lamb with salt and pepper then brown. Stir in the cinnamon. Add enough water to cover, then simmer for about 1 1/2 hours.
In a frying pan melt 40g of the butter then saute the apples, raisins, lemon juice and zest until the apples begin to soften. Stir this mixture into the lamb mixture. Stir in the split peas. Cover and simmer for 30 minutes.