In a large bowl, whisk together the sour cream, applesauce, oil, vanilla extract, and eggs until smooth.
1 cup sour cream, 1/2 cup applesauce, 1/4 cup light olive oil or melted butter, 1 teaspoon vanilla extract, 2 eggs
Add in the flour, sugar, baking powder, baking soda, cinnamon, and salt. Mix the batter until just combined.
2 cups flour, 3/4 cup sugar, 2 teaspoons baking powder, 1/2 teaspoon baking soda, 1/2 teaspoon cinnamon, 1/8 teaspoon salt
Gently fold in the diced rhubarb.
2 cups rhubarb, diced into 1/4 inch pieces
Divide the batter among 13-14 muffin cups using a large batter scoop or spoon. Filling the muffin cups 3/4 way full.
In a small dish, mix the topping ingredients and sprinkle ¼ -1/2 teaspoon of the cinnamon sugar mixture on top of each muffin.
2 Tablespoons sugar, 1/2 teaspoon cinnamon
Bake the muffins for 20-22 minutes or until the muffins are golden brown and a toothpick inserted comes out clean.
Let the muffins cool in the pan for 10 minutes then remove from the muffin pan and place on a cooling rack.
Store the muffins in an airtight container on the countertop for up to 4 days.
Notes
Substitute Tips - Gluten free 1-1 baking flour and whole wheat pastry flour can be substituted for take flour. Storage Tips - The muffins in a ziploc bag for in the freezer for up 3 months.