1. Preheat oven to 400 degrees Fahrenheit. Grease or line a 12-cup mufﬁn tin.
2. In a small bowl, stir together all streusel ingredients until mixture is crumbly. Set aside.
3. In a separate bowl, combine diced rhubarb and 1/3 cup sugar. Set aside.
4. In a large bowl, blend together ﬂour, 3/4 cup sugar, baking powder and salt. Drain rhubarb and stir into ﬂour mixture.
5. In a separate medium bowl, whisk together liquid ingredients; gently stir into the ﬂour-rhubarb mixture until just combined.
6. Divide evenly among mufﬁn cups and top with streusel mixture.
7. Bake 20 to 25 minutes or until light brown and toothpick inserted in the center comes out clean. Serve warm or at room temperature.