Wash, halve and stone the plums. Wash apples, quarter and stone them. Cut into pieces and sprinkle with lemon juice. Spread the fruit in an ovenproof dish.
Mix oat flakes, flaked almonds, grated coconut, brown sugar, maple syrup and coconut oil. Spread the oatmeal mixture over the fruits.
Bake crumble in a preheated oven (electric oven: 200 °C/circulating air: 180 °C/gas: see manufacturer) for approx. 25 minutes until golden brown. Let cool down a little and serve.