Perfect Blueberry Streusel Muffins

Name: Perfect Blueberry Streusel Muffins
Ingredients: For the muffins:; 1 3/4 cups (210g) flour; 1/4 teaspoon salt; 1 tablespoon baking powder; 2 tablespoons lemon powder (optional; you can add 1 teaspoon of lemon zest in its place, if you'd like); 1 egg; 1/2 cup (106g) dark brown sugar; 1/2 cup (113g) plain yogurt; 1/4 cup (50g) vegetable oil; 1/4 cup (56g) milk; 1 1/2 cups fresh or frozen blueberries; For the streusel:; 1/4 teaspoon cinnamon; 1/4 cup (30g) flour; 2 tablespoons packed dark brown sugar; 2 tablespoons melted butter