Begin by preheating your oven to 350 degrees F. Grease a 9×13-inch baking pan with baking spray and then line the bottom with parchment paper, extending it up the sides. Set aside.

In a bowl, mix together the rhubarb, strawberries, lemon juice, and 2/3 cup of sugar. Set aside.

In a separate bowl, beat the butter, remaining sugar, lemon zest, and vanilla with an electric mixer until light and fluffy. Add the eggs one at a time, scraping down the sides of the bowl after each addition.

In another bowl, whisk together the flour, baking powder, salt, and ground ginger.

Gradually add the dry ingredients to the butter mixture, alternating with the sour cream. Start with half of the dry ingredients, then half the sour cream, another half of the dry ingredients, and the remaining sour cream.  Mix until just combined after each addition. Spread the batter evenly in the prepared pan.

Pour the strawberry rhubarb mixture over the batter, spreading it into an even layer.

For the crumb topping, whisk together the flour, brown sugar, salt, and cinnamon. Stir in the melted butter with a fork until crumbs form. Sprinkle evenly over the rhubarb layer.

Bake in the preheated oven for 50 to 60 minutes or until a toothpick comes out clean. Cool completely in the pan on a wire rack.

Use the parchment paper to lift the cake out of the pan. Cut into squares, serve, and enjoy.