In a bowl sift together your flour, cornstarch, baking powder and salt. Using a whisk, mix until well combined. Set aside for now.
In a large bowl add in your sugar, melted butter, vegetable oil, sour cream, vanilla and eggs. Using a whisk, mix until well combined (about 30 seconds).
Add your pre-sifted dry ingredients into your wet ingredients, and using a spatula, gently fold until just combined and there are no more big lumps or streaks of flour. Do not overmix.
Evenly distribute the batter into your cake tin and lightly tap it on your countertop to remove any large air bubbles.
Place the sliced strawberries on top (I like to place mine following a circular pattern - see video demonstration for this), leaving a little bit of space in between each strawberry.
Place the crumble around the strawberries so that you can still see the strawberries. This is optional, otherwise you can just distribute the crumble evenly across the top so that it's covering the strawberries.
OPTIONAL: Finish off by sprinkling the sliced almonds evenly across the top.
Bake for 1 hour, or until a toothpick comes out with a few moist crumbs.
Once baked, allow the cake to cool in the cake tin for 20 minutes. Run a thin knife around the edges of the cake tin to release the cake, and then place a a plate upside down on top of the cake tin and flip the cake tin over. The cake will now be upside down on the plate. Now place your serving plate or cake stand on top the cake, and flip the cake again so it is upright (see video demonstration for this).
Redistribute the almonds if necessary. Dust with icing sugar and enjoy!