Adjust the oven rack to the middle position and pre-heat the oven to 350ºF (180ºC). Lightly butter a 9-inch (23cm) springform pan and line it with parchment/baking paper.
Prepare the strawberries:
Chop about ⅓ of the strawberries into ½-inch (1-1.5cm) pieces.
Slice the remaining strawberries in half.
Set aside until needed.
Add the sugar and lemon zest to a large bowl, and use your fingertips to rub the zest into the sugar.
Tip: This helps to release more essential oils from the zest, and it will make your cake even more lemony and aromatic.
Add the melted butter, oil, buttermilk, eggs and vanilla, and whisk well until combined.
In a separate bowl, whisk together the gluten free flour blend, almond flour, baking powder, baking soda, xanthan gum and salt, and add them to the wet ingredients.
Whisk well until you get a smooth cake batter with no flour clumps.
Transfer about half of the batter into the lined springform pan and smooth it out into an even layer.
Sprinkle the chopped strawberries evenly over the batter.
Dollop the remaining batter over the chopped strawberries, making sure to cover them as much as possible. Smooth out the top.
Arrange the halved strawberries on top of the batter and make sure to pack them as close together as possible. You can arrange them cut side up or down, either way works, I usually do a mix of both for more visual interest.
Bake at 350ºF (180ºC) for about 1 hour to 1 hour 10 minutes or until the cake is well-risen, golden on top and an inserted toothpick comes out clean. If the cake starts browning too quickly, cover it with a sheet of aluminium foil (shiny side up) and continue baking until done.
Allow the cake to cool in the springform pan for about 15 minutes before removing it from the pan onto a wire rack to cool.
Dust it lightly with some powdered/icing sugar before slicing and serving. You can serve it warm or cooled completely to room temperature, with a dollop of lightly sweetened vanilla whipped cream or a scoop of ice cream and some extra strawberries.