Preheat oven to 350°F and line two 12-count muffin tins with paper liners. Set aside.
In a large mixing bowl, combine the flour, baking powder, baking soda, salt, and granulated sugar with a whisk.
2½ cups all-purpose flour, 3 teaspoons baking powder, ½ teaspoon baking soda, ½ teaspoon kosher salt, 1 cup granulated sugar
Add the chopped strawberries, and toss until they are well coated.
2 cups fresh strawberries
In a separate medium mixing bowl, whisk the milk, vegetable oil, and eggs together.
1 cup milk, ½ cup vegetable oil, 2 large eggs
Add the wet ingredients to the dry ingredients, and mix gently with a spoon until completely combined.
Evenly distribute the batter among the 12 cups. Fill each about ⅔ of the way. Set aside.
Add all the streusel topping ingredients to a small mixing bowl, and mix with a fork until well combined.
4 tablespoons unsalted butter, ⅓ cup brown sugar, ⅓ cup granulated sugar, ½ cup all-purpose flour
Sprinkle the streusel evenly over the muffin batter.
Bake for 17-20 minutes, or until the topping is golden and a toothpick can be inserted and come out clean.