Preheat the oven to 180c/160c fan/350f/gas mark 4 and fill a 12-hole muffin tray or 2 x 6-hole muffin trays with paper cupcake or muffin cases.
Measure the oat milk into a jug or bowl, add 2 tablespoon lemon juice and the lemon peel and stir. Set aside.
Add the flour into the bowl and add the other dry ingredients cornstarch, baking powder, sugar, salt and turmeric, if you are adding it). Mix well.
Add the oil to the milk and stir. Pour the wet ingredients into the dry ingredients then mix lightly until just combined.
Pour the batter into the muffin cases and bake the muffins for 20-25 minutes until a skewer or toothpick come out clean and they are springy to the touch.
Leave to cool in the muffin tray for a few minutes and then move to baking rack to cool completely.
While the muffins are cooling, make the icing. Add 2 tablespoon of lemon juice into the icing sugar and mix well until you have a thick, smooth icing. If it needs a little more lemon juice if you need it. It will need less than you think.
Spoon the icing onto the cooled muffins and add some sprinkles.
Enjoy!
Notes
DO NOT OVER MIX THE CAKE BATTER. You will end up with rubbery muffins. Don't worry if there are some lumps or stray flour, it will all be fine.
The cool muffins can be kept in an airtight container in the fridge for 3-4 days.
The muffins (before they are iced) can be frozen for 3-4 months in an airtight, freezer-proof tub for 3-4 months. Defrost in the fridge overnight.