Preheat the oven to 375°F (190°C) and line a muffin tin with liners.
In a small bowl, whisk together flour, baking powder, and salt.
In a medium bowl, whisk together sugar and oil. Add egg white, sour cream, vanilla, and lemon zest. Whisk until smooth. Stir in flour mixture until just combined (do not over-mix). Fold in blueberries.
Divide batter between prepared muffin cups, filling each just under 2/3 full. Optional: sprinkle the tops with a little extra sugar if desired.
Bake for about 16 to 22 minutes, until a toothpick inserted into the center comes out with just a few dry crumbs and when gently pressed, the top of the muffin springs back.
Cool in the pan for 5 minutes before transferring to a cooling rack.
Make the latte: Heat the chai concentrate and milk in a saucepan. Simmer on low for 4-5 minutes, stirring occasionally.
Finish the latte: Pour the heated chai latte into a French press or use a frother or whisk.
Place the lid on the French press and move the plunger up and down 20 times. Make sure to hold onto the lid as you move the plunger. The chai latte will double in volume. Alternatively, use a frother or whisk by hand until the latte doubles in volume. Pour the chai latte into a mug. Add sugar to taste if needed. Dust with cinnamon.
Enjoy the muffins with a latte.