Place your walnuts in a mug and cover with hot water. Leave to soak while you roast the strawberries.
Cut the strawberries in half and lay flat down on a baking tray lined with parchment paper.
When the oven is ready, roast the strawberries for about 20 minutes, or until they are soft and starting to release juices.
Blend all ingredients except for the oat flour until smooth. It will take a while to get everything nice and creamy. Add the oat flour in last, and pulse until it's blended in.
Notes
I suggest using a hand blender for this puree, but if you are going to use a mini food processor or jug bender, scale up the quantities so that it's able to puree properly.