Stir the flour, salt and yeast together in a large bowl. Slowly add in the warm water while stirring constantly until a dough forms. It will be sticky! Once the lumps are gone and the dough is combined, cover it and place in a warm spot to rise for 1 to 2 hours.
Brush an 18x13 inch sheet pan with 2 tablespoons of the melted butter. Drizzle on the oil and brush it all over the pan too. Turn the dough out onto the pan and press it out with your hands until it covers the sheet pan.
Place the baking soda in a large bowl. Bring ½ cup water to a boil (I use an electric tea kettle for this) and pour it over the baking soda. It will get foamy - this is why you want to use a bigger bowl that you’d expect.
Brush the mixture (you won’t use all of it - reserve it to use later) on the top of the dough. Then place the sheet pan in a warm place and let it rise again for an hour. It will be a little bubbly too.
Preheat the oven to 475 degrees F. Brush the top of the dough again with the baking soda mixture. Bake the bread for 10 minutes. Remove the pan and brush it with the remaining melted butter. Sprinkle with the flaked salt and sesame seeds. Return the pan to the oven and bake for another 10 to 15 minutes, until the top is golden brown (like a soft pretzel!) and the edges are a bit crisp.
Let the bread cool slightly (you can make the beer cheese while it cools!) before slicing it. Serve!