In a large mixing bowl, combine sugar, vanilla, strawberry extract, melted butter, buttermilk, and eggs. Whisk to combine well.
In a separate medium bowl, whisk together the flour, salt, and baking powder.
Remove 2 tablespoons of the flour mixture and sprinkle over the rhubarb and strawberries. Toss to coat. This will help prevent the strawberries from sinking to the bottom of the baked loaf.
Mix the remaining flour mixture into the wet ingredients until just combined.
Fold the strawberry rhubarb mixture into the batter to distribute evenly, but do not overmix.
Pour batter into a greased or parchment-lined 9×5-inch loaf pan.
Bake for 55 to 60 minutes. Test the bread by inserting a toothpick into the center. It should come out clean or with a few moist crumbs attached.
Remove from the oven and cool. You can turn the bread out onto a wire cooling rack after it has cooled for an initial 10 minutes in the pan.
For the glaze, whisk together the powdered sugar, buttermilk, and strawberry extract.
Drizzle the glaze over the bread after it has cooled completely.
Slice into 8 slices with a serrated knife and serve.