Preheat your oven to 350 degrees Fahrenheit. Line a square baking dish with parchment, set aside.
Start by preparing the strawberry layer. In a bowl, combine strawberries, lemon juice, flour, and sugar, and combine. Set aside while you prepare the rest of the cake.
For the cake batter, mix together the butter and sugar. Add the vanilla, eggs, sour cream, and buttermilk, and mix well.
Add the baking powder and salt to the flour, and whisk. Then, slowly add the dry ingredients to the wet, mixing until just combined.
Pour the batter into the parchment lined baking dish.
Carefully sprinkle the strawberry mix evenly over the cake batter.
For the crumb topping, in a mixing bowl, combine the flour, sugar, brown sugar, and melted butter until combined.
Sprinkle this mixture over top of the strawberries.
Bake at 350 for 50-60 minutes. The crumb topping will be golden brown, and you should be able to insert a toothpick into the center of the cake without any wet cake batter. If needed, add cook time 5 minutes at a time until the cake is baked through.