Filling:
2 cups sliced rhubarb (1/2-inch thickness)
1 pint strawberries, cleaned, hulled, and sliced
1 tablespoon lemon juice
2/3 cup granulated sugar
3 tablespoons cornstarch
Over medium high heat start cooking the fruits with the lemon juice. Mix together the cornstarch and sugar until all the lumps are worked out of the starch. If you don't do this, there will be icky specks of white all throughout your fruit and they neither taste nor look appetizing. Bring this to a simmer, stirring often. The fruit will start to break down and thicken up. Once you see this, turn off the heat and set aside to cool.
Cobbler:
1 1/2 cups all-purpose flour
1/4 teaspoon baking soda
1 teaspoon baking powder
1/4 teaspoon salt
1 stick butter, softened
3/4 cup granulated sugar
2 large eggs
1/2 cup sour cream
1 1/2 teaspoons vanilla
Preheat the oven to 350 degrees
Cut the butter into the flour until it's the consistency of a crumble
Add all the other dry ingredients (baking soda, baking powder, salt, and sugar)
Add the eggs, sour cream, and vanilla
Grease and flour a 9x9 inch pan if you want a thicken cake, otherwise a 9x13 will work. I did not flour the pan below. So I shall reiterate: grease and flour your pan. Add about 2/3 of the cobbler mix to the bottom of the pan, then all the fruit mixture. Dot the remaining cobbler over the surface of the fruit. This doesn't have to completely cover the fruit - it's actually really pretty to have the fruit peeking out from underneath. I don't have a picture of this...probably because I was licking the spoon with remaining fruit mix at the time...my kitchen, my rules. Bake about 35 minutes for a 9x13 and 45 for a 9x9. The top will be slightly brown and the cake should be cooked through when tested with a toothpick.