In a small bowl, combine dried cranberries with 1 tbsp orange juice or warm water.
Let soak 10–15 minutes, then drain and pat dry.
Preheat oven to 350 F. Line 16 muffin cups with liners.
In a stand mixer or with a hand mixer, beat ¾ cup butter on medium-high until smooth. Add 1 cup sugar and beat until pale and fluffy. This is the best
Add eggs one at a time, beating well after each addition. Scrape the bowl as needed.
Beat in 2 tsp vanilla extract and 1 tbsp orange zest until fully combined.
In a separate bowl, whisk together 1 ¾ cups flour, ¼ cup cornstarch, 1 ½ tsp baking powder, and 1 tsp salt.
In another small bowl or measuring cup, whisk together ⅔ cup milk and ½ cup sour cream until smooth.
With the mixer on low, add ⅓ of the dry ingredients and mix until most ingredients are incorporated. Mix ½ of the wet ingredients and mix until just combined, repeat steps until both dry and wet ingredients are added and stop as soon as no dry streaks remain.
Using a spatula, gently fold in the plumped cranberries.
Divide batter evenly among the liners (about ¼ cup per liner). Bake 18–22 minutes, or until the tops are pale golden and spring back lightly when touched.
Let cupcakes cool in the pan for 5 minutes, then transfer to a wire rack to cool completely before frosting.