Time to dust off your bundt pan and bake your mom (or dad) a special summer treat! This buttermilk strawberry rhubarb bundt cake is moist, tender, packed full of fresh fruit, and topped with a zingy orange glaze. A surefire crowd pleaser!
In a large bowl, whisk together the flour, baking power, baking soda and salt. In a medium bowl, whisk the orange juice with the vanilla extract and buttermilk. In a small bowl, whisk the eggs and yolk to combine.
Now it's time to mix in the flour and the buttermilk. Turn the mixer on low; add ⅓ of the flour mixture and mix until just incorporated. Then add ½ of the buttermilk mixture, again mixing until just incorporated. Continue adding in turns - ⅓ of the flour, the remain ½ of the buttermilk, and the last ⅓ of the flour. When the last of the flour is almost mixed in, remove the bowl from the mixer. Then add half of the strawberries and rhubarb. Use your spatula to give the batter a few swift stirs to finish mixing and incorporate the fruit. (If you don't have a standing mixer, you can use a hand mixer. Just increase the mixing time for the butter and sugar to 6-7 minutes.)
Dollop the batter into the prepared pan, adding spoonfuls evenly around the circle of the Bundt pan. Pour remaining strawberries and rhubarb over the top and push gently into the top of the batter.
For the glaze: Whisk together the orange juice, orange zest, buttermilk, and confectioners' sugar until smooth and very thick. The glaze should be just liquid enough to flow thickly off the whisk. If it doesn't flow, add more buttermilk by the ½ tablespoon until it does. Spoon the glaze evenly over the top of the cooled cake until it looks like there is enough on it. Don't worry if it doesn't look smooth and pretty at first; the glaze will slowly work its way down the cake. Cut into slices and serve.