Preheat oven to 350°F. Grease a 9-inch springform pan and line the bottom with parchment paper.
In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set aside.
In a stand mixer (or using a hand mixer), cream the butter and sugar until light and fluffy, about 2–3 minutes.
Add eggs one at a time, mixing well after each. Stir in the vanilla, lemon zest, and lemon juice.
Add the Greek yogurt and milk, and mix until smooth.
Gradually add the dry ingredients and mix just until combined—don’t overmix!
Gently fold in the chopped strawberries and rhubarb.
Pour the batter into the prepared pan and smooth the top. Sprinkle with a little sugar if desired for a golden crust.
Bake for 50–60 minutes, or until a toothpick inserted into the center comes out clean.
Remove to a wire rack. Let cool in the pan for 10–15 minutes before removing.
Cool completely before topping with powdered sugar and slicing.
