Preheat your oven to 350°F
Make the lemon crumb topping by combining 1 cup flour, sugar, salt and lemon zest with the melted butter. Using your fingers, mix it around until its crumbly and set aside.
Butter and flour 2 cupcake tins.
Toss the blueberries with the 2 tbsp of flour and set aside
In small bowl, sift together the flour, baking powder, baking soda, and salt and set aside.
In a large mixer combine the butter and sugar until pale yellow, add the zest, eggs, and vanilla bean and beat well for an additional 2-3 minutes making sure to scrape down the sides.
Alternate adding the flour, and the buttermilk until all is combined, making sure to scrape down the sides during the process.
Spoon 1/4 cup of the batter into each cupcake mold. Top with some of the floured blueberries. Sprinkle the top with some of the crumb mixture.
Bake for approximately 30 - 35 minutes, or until the cake is light and fluffy.
Remove from oven and let cool before serving.