Vegan Strawberry Streusel Cake

For the topping:
⅓ cup flour
⅓ cup sugar
¼ teaspoon ground cinnamon
4 teaspoons vegan butter
2 tablespoons water

For the cake:
2 cups flour
½ cup sugar
1 tablespoon baking powder
½ teaspoon ground cinnamon
¼ teaspoon salt
2 tablespoons vegan butter, melted
½ cup unsweetened applesauce
½ cup vegan milk or fruit juice
1-½ teaspoon vanilla extract
Safflower oil, for oiling pan
1 pint strawberries, washed, destemmed, and sliced
Powdered sugar, for serving