Preheat oven and prepare pan:

Preheat oven to 375°F (190°C). Line a 12-cup muffin pan with paper liners or grease thoroughly.

Whisk dry ingredients:

In a medium bowl, whisk together 2 cups (250g) all-purpose flour, 2 teaspoons baking powder, 1/2 teaspoon baking soda, and 1/4 teaspoon salt. Set aside.

Cream butter and sugar:

In a large bowl, whisk 1/2 cup (113g) melted and cooled unsalted butter with 3/4 cup (150g) granulated sugar until combined. Add 2 large eggs one at a time, whisking thoroughly after each addition.

Add wet ingredients:

Stir in 1/2 cup (120ml) whole milk, 1/4 cup (60g) sour cream or plain yogurt, 1 teaspoon vanilla extract, and 1 tablespoon finely grated lemon zest until smooth.

Fold dry into wet:

Gently fold the dry ingredients into the wet mixture until just combined, being careful not to overmix.

Fold in strawberries:

Fold 1 1/2 cups (225g) diced fresh strawberries into the batter with a gentle hand.

Fill muffin cups:

Divide the batter evenly among the prepared muffin cups, filling each about 3/4 full.

Make crumble topping:

In a small bowl, combine 1/2 cup (63g) all-purpose flour, 1/3 cup (67g) packed light brown sugar, 1/4 teaspoon salt, and 1/2 teaspoon finely grated lemon zest for the crumble topping. Add 1/4 cup (57g) cold cubed unsalted butter and mix with a fork or fingertips until the mixture resembles coarse breadcrumbs.

Sprinkle crumble on batter:

Sprinkle the crumble mixture evenly over the batter in each muffin cup.

Bake muffins:

Bake for 22 to 25 minutes until tops are golden brown and a toothpick inserted into the center comes out clean.

Cool muffins:

Allow muffins to cool in the pan for 5 minutes, then transfer to a wire rack to cool completely.