Preheat oven to 425 degrees F and grease muffin tins with butter or muffin liners with cooking spray.
In a medium sized pan over medium heat, melt the butter with the tea bag and vanilla bean over medium heat. Swirl occasionally to ensure butter is cooking evenly and the flavors of the tea and vanilla are infused. As the butter melts, it will begin to foam and the color will get darker. Continually scrape bottom of pan to release any brown specs. Once you start smelling the nutty aroma, remove browned butter from heat and allow to cool.
In a large bowl, sift together flour, sugars, baking power, baking soda, and salt.
In a separate bowl, whisk eggs, buttermilk, vanilla, and mostly cooled browned butter together. Make a well in the dry ingredients and pour in the liquid ingredients. Fold together and do not over mix.
Spoon batter into greased muffin tins and bake in preheated oven for 5 minutes. Without opening the oven door, reduce heat to 325 degrees F and continue cooking until golden brown, about 15-25 minutes (mine took longer because I used a stone muffin pan). When done cooking, immediately remove from muffin tins and allow to cool on cooling rack.