Preheat the oven to 425.

Toss rhubarb, strawberries, honey, lemon juice and arrowroot in a bowl to combine.

Pour fruit mixture into an 8 x 8 baking dish.

In a separate bowl, add rolled oats, cassava flour, coconut sugar, and salt and toss to combine. Add the ghee and blend together until small clumps begin to form.

Sprinkle the oat topping evenly over the fruit.

Bake in the oven for 20 minutes until the crisp is golden brown and the fruit is bubbling underneath.