Lemon Blueberry Muffins (Dairy-free, Nut-Free, Egg-Free, Soy-Free)

Still tweaking this one.. But here's what I have so far:

2 cups all-purpose flour
1/2 cup white sugar
3 tsp baking powder
1 Tbsp lemon juice
1/4 tsp salt
1 cup of water/rice milk
1/3 cup of vegetable oil
1 egg (or egg-replacer)
2 tsp vanilla flavouring
1 banana- mashed
1 cup fresh blueberries

Preheat oven to 350 degrees F
Line muffin tins with paper muffin cups
Mix all ingredients in bowl. Add the blueberries last.
Mix until smooth
Bake for 25-30 minutes