Preheat oven to 425 F degrees. Spray two 12 count mini muffin pans with non stick spray and set aside.
In a bowl whisk together flour, salt, baking soda and cinnamon powder. Set aside.
In another bowl prepare the streusel, mix together flour, brown sugar, rolled oats, chopped pecans and cinnamon powder. Cut in the cold butter using a pastry cutter or 2 forks till the mixture resemble coarse crumbs. Set aside.
Using the paddle attachment of your stand mixer or using your hand mixer, beat together oil, sugar and vanilla extract till well combined.
Add in 2 large eggs and mix till well combined. Now add the mashed bananas and mix.
Add in the half of the flour mixture and mix till combine.
Add greek yogurt and mix. And then add the remaining 1/2 of the flour mixture and mix till just combined. Do not over-mix.
Fold in the blueberries [remember do not thaw the blueberries if using frozen].
Fill the muffin pan till 3/4 full. Then top each muffin with the streusel topping all the way to the top.
Bake at 425 F degrees for 3 minutes and then lower the temperature to 350 F degrees (with the muffins inside the oven) and bake for another 8 minutes or till a toothpick inserted in the center comes out clean.
Transfer the mini muffins on to a wire rack to cool completely.