Rhubarb Loaf with Brown Sugar

Instructions:

1. Preheat oven to 325°F (165°C). Grease a 9x5 inch loaf pan and line it with parchment paper.
2. In a small bowl, toss the diced rhubarb with lemon juice and 2 tablespoons of flour until lightly coated; set aside.
3. In a large bowl, whisk together brown sugar, oil, and egg until smooth and slightly pale.
4. Stir the buttermilk and vanilla extract into the sugar mixture.
5. In a separate bowl, sift together the flour, baking soda, and salt, then gently fold the dry ingredients into the wet mixture using a spatula until no streaks of flour remain.
6. Fold the coated rhubarb into the batter with two quick turns.
7. Pour the batter into the prepared loaf pan.
8. In a small bowl, rub together the flour, brown sugar, cubed butter, and cinnamon with your fingers until coarse crumbs form, then sprinkle evenly over the batter.
9. Bake for 55 to 60 minutes, or until the top is deep mahogany brown and a skewer inserted into the center comes out with a few moist crumbs.
10. Let the loaf cool in the pan for 10 minutes before transferring to a wire rack.