Rendering the Strawberries
First, chop up the strawberries into small pieces (if fresh), and then put them into a sauce pan over medium heat. Use a potato masher to mash the strawberries into a liquid. Once, the strawberries are mostly mashed, remove them from the heat and set aside.
Donut Dough
Next, add all purpose flour, salt, and baking soda to a medium bowl and set aside.
Then, mix together the strawberries, sourdough discard, sour cream, egg, lemon juice and zest, and vanilla extract together in a large bowl and set aside. Be careful not to overmix.
Now, mix the melted butter and the sugar together. Add the butter-sugar mixture and the dry ingredient mixture to the strawberry mixture. Mix everything together.
Next, prepare your donut pan adding any cooking grease if needed. And then, add the dough to a pipping bake or a Ziplock bag and pipe the dough into the donut pan so that each donut cavity is about 3/4ths full.
Place the donut pan in the oven for about 12 minutes. You will be able to tell when the donuts are done because they will feel springy/spongy to the touch.
When the donuts are done, pull them out of the oven and let them cool a little before glazing. Enjoy!
Donut Glaze (Optional)
Start with powdered sugar in a medium sized mixing bowl and then add 1/4 cup of half and half and vanilla extract and mix until smooth. If you want a thinner consistency, add another 1/4 cup and so on to make the glaze the consistency that you want it to be.
Finally, use a silicone spatula or butter knife to spread the glaze on the donuts and enjoy!