Preheat the oven to 350.
Grease or use parchment paper on a 9x5-inch loaf pan.
FOR THE BREAD: In a large bowl, mix by hand or with an electric mixer, the sugar, vanilla, vanilla extract, melted butter, buttermilk, and eggs. Blend until all is incorporated.
Mix together the flour, baking powder and salt and and it to the mixture. Blend well.
Coat rhubarb and strawberries with the heaping 1 tablespoon of flour. This prevents the fruit from sinking to the bottom. Gently fold the coated fruit into the mixture.
Pour the batter evenly into the prepared pan.
FOR THE TOPPING: If desired, top with additional pieces of diced strawberries and rhubarb.
Bake at 350 for 55 to 60 minutes or until a tester inserted in the middle comes out clean.
Cool the bread in the pan on a wire rack for 10 minutes, then invert it onto a serving plate.
FOR THE GLAZE: If desired, mix the glaze ingredients and drizzle it on top of the cooled bread.
If desired, drizzle the bread with the glaze or leave it plain.
Store in the bread covered on top of the counter.