Preheat your oven to 350°F and line muffin pans with cupcake liners (you'll need about 24 liners). In a medium bowl, whisk together the flour, baking powder, baking soda, and salt. Set this dry mixture aside—this ensures your leavening agents are evenly distributed throughout the batter, which gives you those light, tender crumbs we want in cupcakes.

In a large mixing bowl, beat the room-temperature butter and granulated sugar together for about 5 minutes until the mixture is pale, fluffy, and noticeably lighter in color. This creaming process is crucial—it incorporates air into the batter, which helps your cupcakes rise evenly and achieve a tender crumb. Don't skip this step or rush it; the extra time really makes a difference in texture.

Add the room-temperature eggs one at a time to your creamed butter mixture, beating well after each addition to fully incorporate. This gradual process prevents the batter from breaking and helps create an emulsion. Once all eggs are in, add the vanilla extract and mix until combined. Room-temperature eggs are important here—cold eggs won't incorporate smoothly and can result in a curdled batter.

In a small bowl, whisk together the sour cream and whole milk to create a combined wet mixture. Now, alternately add the dry ingredient mixture from Step 1 and the wet mixture to your butter-egg mixture, beginning and ending with the dry ingredients (dry, wet, dry, wet, dry). Stir gently after each addition until just combined—overmixing develops gluten and makes cupcakes tough. I like to use a rubber spatula and fold gently rather than beating at this stage to keep the batter tender.

Gently fold the finely diced fresh strawberries and pink food coloring (1-2 drops, depending on desired color intensity) into your batter until just combined. The delicate folding preserves some strawberry pieces for texture and distributes the color evenly throughout. Divide the batter evenly among your prepared cupcake liners, filling each about two-thirds full, then place the pans in your preheated oven.

Bake for 20 to 25 minutes, until a toothpick inserted into the center of a cupcake comes out clean or with just a few moist crumbs. Let the cupcakes cool in their pans for about 5 minutes, then transfer them to a wire rack to cool completely before frosting. This prevents the residual heat from melting your frosting when you apply it.

While the cupcakes cool, prepare your frosting. In a clean mixing bowl, beat the softened butter and salt together for about 5 minutes until smooth and creamy. Gradually add the sifted powdered sugar, beating on low speed to avoid creating a cloud of sugar dust, then increase speed and beat until fluffy. Add the concentrated strawberry puree, vanilla extract, and fresh lemon juice, then beat for about 1 minute until well combined and the color is uniform throughout.

Using an offset spatula or piping bag with a large round tip, frost each completely cooled cupcake generously with the strawberry buttercream from Step 7. Top each frosted cupcake with a fresh strawberry slice or whole berry if desired for a beautiful presentation and fresh strawberry flavor that complements the frosting perfectly.