Preheat your oven to 375 degrees F and line a standard muffin pan with paper liners. Spray lightly with oil.
In a large bowl, whisk together all the dry ingredients: flour, sugar, baking powder, cornstarch and salt.
Pour in the melted vegan butter, soy milk and vanilla. Stir with a large spoon until just combined, but do not over mix or your muffins will be dense.
Fold in the strawberries, gently.
Using a small measuring cup or ice cream scoop, transfer the batter to the prepared liners and fill 3/4 of the way full.
Make the crumb topping: In a small bowl, combine all ingredients and mix with a fork until crumbly.
Sprinkle the crumb all over the tops of the muffin batter.
Bake for 20-25 minutes, until slightly golden brown on top and a toothpick inserted comes out clean. Let them cool for at least 5 minutes in the pan, then transfer to a cooling rack.
Store muffins in an airtight container at room temperature for about 3 days, or up to 1 week in the refrigerator. They also freeze well.