Preheat oven to 350 degrees F and grease an 8x4" loaf pan. Line with parchment paper if you want to remove bread completely from the pan after baking.
In a large mixing bowl, whisk flour, salt, baking soda, and 2-3 tbsp of very strong matcha. Use 2 tbsp for a mild flavor and 3 tbsp for a more prominent matcha flavor.
In a separate bowl, mix your wet ingredients: mashed bananas, eggs, brown sugar, butter, sour cream, and vanilla bean paste.
Mix wet and dry ingredients together until you have a batter with no dry lumps remaining.
Transfer batter to your greased and lined baking tin and bake for one hour. Check for doneness by sticking a wooden skewer down the center of your bread. If the skewer comes out with wet batter, continue baking until the skewer comes out clean, up to 10-15 minutes more.
Allow banana bread to cool to room temperature, then slice and serve.