Preheat the oven to 425°F/218°C. Line a standard 12-cup muffin tin with liners.
Zest the lemon, them juice it. Mix the almond milk with the 1 tablespoon lemon juice and set aside to curdle.
In a large bowl, whisk together the flour, almond flour, baking powder, and salt. Make a well in the center and add in the lemon zest, almond milk-lemon juice mixture, yogurt, maple syrup, mashed banana, oil, and vanilla.
Stir the wet ingredients into the dry using a wooden spoon, stirring until it’s just mixed – about 10 to 12 strokes. The batter should be lumpy and not terribly smooth. Don’t overmix, as it will cause the muffins to become dense.
In a small bowl, add all the ingredients for the Streusel Topping. Stir together with a fork until well combined a bit sticky.
Scoop the muffin batter evenly into each lined muffin cup. Top each muffin with a generous amount of the Streusel Topping.
Add the muffin pan to the oven and then reduce the temperature to 350°F/177°C. Bake for 25 minutes or until a toothpick inserted in the center comes out with just a few crumbs. Cool on a wire rack for 10-15 minutes before enjoying.