Blueberry Muffins with Sour Cream

Instructions:

1. Whisk together the flour, sugar, baking powder, and salt in a large bowl until no clumps remain.
2. Create a well in the center of the dry ingredients and add the sour cream, eggs, oil, and vanilla extract.
3. Gently fold the wet and dry ingredients together with a spatula until flour streaks just disappear; do not overmix.
4. Toss the blueberries in 1 tablespoon of flour, then fold them gently into the batter.
5. Divide the batter evenly among 12 cups of a standard muffin tin.
6. Combine streusel ingredients (flour, brown sugar, cinnamon, and cold butter) using your fingers until the mixture resembles wet sand.
7. Press a generous pinch of streusel topping onto each muffin.
8. Bake using a high heat start until the edges are mahogany-colored and a toothpick inserted into the center comes out with a few moist crumbs.