Heat oven to 200C/180C fan/gas 6. Sift the flour into a bowl and add the margarine.
Using a fork or your hands, mash together the margarine and flour until it resembles breadcrumbs and there are no remaining lumps of margarine.
Add the oats, sugar, and cinnamon to the flour and margarine mixture.
Core the apple and/or pears, and stone the plums, if using. Chop all the fruit, keeping the skin on for added flavour, vitamins, and minerals, and put in an
ovenproof dish in layers.
Drain the sultanas and add to the fruit. Drizzle with the honey.
Sprinkle over the crumble mixture. Bake for 20-30 mins until the crumble topping is golden and the fruit is bubbling. Serve with a large spoonful of natural yogurt, ice cream or crème fraîche.