Wash and slice both strawberries and rhubarb. Place into the base of the slow-cooker. Sprinkle monk-fruit sweetener and cornstarch (if using) and toss to combine.
In a separate bowl combine oats, cinnamon, salt, flour, flax and chopped walnuts. stir to combine.
Melt coconut oil and add to oat mixture with maple syrup. Mix thoroughly. Scatter topping over the fruit. Cover with the lid and turn slow-cooker on high. Leave to cook for 2 hours.
After 2 hours, remove the lid and scoop portions into bowls. Top with coconut kefir or yogurt. If making for dessert, add vanilla ice-cream and extra fruit.
Notes
For an overnight method, follow above instructions but turn the slow-cooker to the low setting and serve the next morning.