Preheat your oven to 350 degrees.
Combine all the dry ingredients (flour, sugar, baking soda, and salt) in a large bowl.
In another bowl, combine the wet ingredients (oil, yogurt, and egg).
Pour the wet ingredients on to the dry ingredients, then add the strawberries & rhubarb.
Mix to just bring the batter together. Don't not over mix the batter. If there are a few lumps don't worry about it, they will work themselves out.
Place 12 muffin liners into your muffin pan. Fill each one about ⅔rds the way up.
Evenly distribute the crumble topping onto each muffin.
Bake for about 20 to 25 mintues, until golden brown on top and cooked all the way through. Remove from pan as soon as you can handle them.