Preheat your oven to 350°F (175°C) and line a 12-cup muffin tin with cupcake liners. In a medium bowl, whisk together the flour, baking powder, and salt until evenly combined.

In a large bowl, beat the softened butter and sugar with a hand mixer on medium speed for 2 minutes until light and fluffy. Add the oil and beat for another 30 seconds until fully incorporated.

Add the eggs one at a time, beating well after each addition. Mix in the sour cream and vanilla extract until the batter is smooth and creamy.

Add half of the flour mixture to the batter and mix on low speed just until mostly combined. Pour in the milk and mix briefly, then add the remaining flour mixture. Mix just until no flour streaks remain, being careful not to overmix.

Divide the batter evenly among the cupcake liners, filling each about two-thirds full. Bake for 18-22 minutes, until a toothpick inserted in the center comes out clean and the tops spring back when lightly pressed. Let cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.

While the cupcakes cool, toss the diced strawberries with 3 tablespoons of sugar in a bowl. Let them macerate at room temperature for at least 20 minutes, stirring occasionally, until they release their juices and create a syrup.

Pour the cold heavy cream into a chilled bowl and beat with a hand mixer on medium-high speed until soft peaks begin to form, about 2 minutes. Add the powdered sugar and vanilla extract, then continue beating until stiff peaks form, about 1 more minute.

To assemble, spoon a generous dollop of whipped cream onto each cooled cupcake. Top with a spoonful of the macerated strawberries and a drizzle of the strawberry syrup. Serve immediately or refrigerate for up to 4 hours before serving.