1) Add 1 tbsp oil into large saucepan. Saute the onion and green pepper until tender.
2) Over low heat in a medium saucepan, add butter and flour. Stir together. Slowly add single cream while whisking, about 2 mins. Add tomato ketchup, mustard and bread crumbs. Mix to combine. Allow to simmer for a few mins. Add crabmeat and lemon juice. Season with salt and pepper, to taste.