Heat the oven to 350°F (175°C). Grease the pan and add a parchment sling. Keep the tablespoon of berry flour separate from the main flour.
Whisk the 2 cups flour, baking powder, and salt. Rub lemon zest into granulated sugar in a separate large bowl until fragrant.
Whisk eggs, oil, milk, yogurt, lemon juice, and vanilla into the citrus sugar until the wet mixture looks uniform.
Fold the dry mixture into the wet ingredients just until almost combined. Toss blueberries with their tablespoon of flour and fold gently into the batter.
Scrape into the pan and level the top, spreading blueberries evenly. Avoid stirring repeatedly, which can break berries and streak the crumb.
Bake 50–60 minutes, until a center tester shows no raw batter. If it strikes a juicy blueberry, check another nearby spot.
Cool in the pan 15 minutes, then lift onto a rack and cool about 1 hour. Tent the top during baking if it darkens before the middle cooks.
Cut after cooling with a serrated knife. This quick-bread version uses oil and yogurt and is served plain, keeping it distinct from the glazed butter-based loaf cake.
