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1
: In the bowl of a stand mixer add yeast, warm water, and one teaspoon sugar. Cover and set aside for 5 minutes or until foamy.
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2
To the yeast mixture add 2 cups flour, sugars, cinnamon, salt, sour cream, egg, lemon zest, and vanilla. Mix on medium speed until just combined, about 45 seconds, then beat in butter, one tablespoon at a time, until thoroughly combined. Continue beating at medium speed until dough is smooth and shiny, about 5 minutes. The dough should be very sticky and stick to the sides of the bowl. Transfer dough to a large greased bowl, cover and let rise in a warm spot until almost doubled, 2 to 3 hours.
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3
Grease an 8-inch baking dish. Spread the dough into the pan and cover with plastic wrap and let rise in a warm and draft-free spot until almost doubled, 1 1/2 hours to 2 hours.
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4
: While your dough is doing its second rise, add strawberries, rhubarb, sugar, orange juice, vanilla and corn starch to the bowl of a food processor. Pulse to puree the fruit. Transfer fruit mixture to a small saucepan and heat over medium, stirring frequently until the mixture thickens. Transfer thickened mixture to a medium bowl and refrigerate until cooled, about 1 hour.
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5
: Rinse and dry the bowl and blade for your food processor and add butter, sugars, flour, ginger and cinnamon. Pulse until small crumbs form. Transfer to a medium bowl and set aside.
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6
Once dough is ready, set the rack to the middle position and preheat oven to 375u00b0F. Transfer covered dough to refrigerator for 20 minutes to firm it up slightly before adding toppings.
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7
Transfer cooled filling to a piping bag fitted with a large round tip and pipe wide stripes of filling across the top of the cake dough. Use a spreading knife to smooth over filling to cover the entire surface. Toss crumbs, working them with your hands to form them into larger clumps and then sprinkle them over the entire surface of the cake. Bake until crumbs are golden brown and a cake tester inserted in the center of the cake comes out clean, 35 to 45 minutes. Remove, cool and serve. Cover leftovers and store up to a day.
