Preheat oven to 350 degrees F and grease your loaf pan.
In a large bowl, add the lemon zest to the sugar and rub it in with your fingertips until the sugar is damp, sandy, and fragrant. This releases the lemon oils for a brighter flavor.
1 ⅓ cup white sugar, 2 tablespoons lemon zest
Add the Greek yogurt (or sour cream), oil, eggs, vanilla, and lemon juice to the lemon sugar. Whisk until smooth and the sugar has dissolved.
⅔ cup greek yogurt or sour cream, ¾ cup vegetable oil, 3 large eggs, 1 tablespoon vanilla extract, 2 tablespoons fresh lemon juice
Add the flour, baking soda, and salt to the wet ingredients. Mix just until the flour is incorporated. Do not overmix.
2 ⅓ cup all-purpose flour, ¾ teaspoon baking soda, ¼ teaspoon salt
In a separate small bowl, toss the blueberries with the reserved 1½ tablespoons of flour until lightly coated. This keeps them from sinking.
2 cups fresh or frozen blueberries
Gently fold the floured blueberries and walnuts into the batter until they're just combined.
1½ cups chopped walnuts
Pour the batter into the greased loaf pan and bake for about 1 hour 30 minutes to 1 hour 45 minutes, until the top is a deep golden brown and a toothpick inserted in the center comes out clean. If the crust darkens too quickly, tent loosely with foil.
Turn out onto a wire rack to cool completely before slicing. Serve and enjoy!