Mix wet ingredients first, then add the dry ingredients and mix to combine.
Add the lemon juice last, and give it one last gentle mix to activate the baking soda and powder. You should have a batter consistency similar to a cake batter.
Fill muffin cups.
Streusel is optional, you can skip it if you want.
Make the streusel: in a separate small bowl combine the cinnamon, same gluten free flour, sugar and cold butter (small cubes).
Mix and rub the butter with your fingers with the rest of ingredients until you get small crumbs. Sprinkle on top of each muffin. Tap the tin to set.
Bake for 30 minutes.
Notes
As fat - you can use regular butter, non -dairy butter, ghee, vegan ghee, coconut oil, avocado oil - these are my "clean" options. Melt and mix as you like.
Flour - you can use regular flour or your favorite gluten free flour mix, but you might need to adjust the amount (probably add a bit more). Since I used my whole grain gluten free flour mix, this formula tends to absorb a bit more liquid when compared to other fine starchy flours.
Optional add-ons - mix some seeds/nuts (hemp, pumpkin, walnuts) + dried fruit (cranberry, raisins, mango, prunes) in the batter. Make your own combination.