Preheat oven to 425 degrees. Lightly grease a muffin tin with butter or non-stick cooking spray.
In a small mixing bowl, start your streusel topping. Combine ⅓ cup brown sugar, 1 tsp ground ginger and ½ cup flour together. Add melted butter and mix until the mixture resembles clumpy sand. Set aside.
In a medium mixing bowl or stand mixer, cream together ½ cup softened butter, ½ cup brown sugar and ¼ cup granulated white sugar. Add eggs, one at a time, mixing well after each. Add yogurt and vanilla extract and mix well.
In a fresh bowl, combine the dry muffin ingredients: 1¾ flour, 1 tsp baking soda, 1 tsp baking powder and ½ tsp salt. Mix the wet ingredients into the dry ingredients. Fold in strawberries and rhubarb.
Distribute muffin batter into all 12 spaces in the muffin tin- the batter should come almost all the way to the top of each spot. Evenly distribute the streusel topping over each muffin.
Bake for 5 minutes then reduce the temperature to 350 degrees and bake for an additional 12-15 minutes, until a toothpick inserted into the centre of the largest muffin comes out clean.
Notes
* Basic muffin recipe adapted from Sally's Baking Addiction: http://sallysbakingaddiction.com/2014/06/10/glazed-apple-crumb-muffins/
Recipe by Port and Fin at https://portandfin.com/strawberry-rhubarb-streusel-muffins/