For the Oven Dried Tomatoes: Preheat the oven to 250F. Using a small knife cut an x into the top of the tomato, then place into a pot of boiling water for 30 seconds remove from the water and place the tomato into an ice bath.
Once the tomato has cooled take it out of the ice bath and peel the outside skin off of the tomato starting at the top were you placed the “X” prior to boiling. Cut the tomato into 4 wedges and place on a rimmed baking sheet. Bake for about 2 hours.
For the Beer Cheese: In a medium sauce pot melt the butter. Whisk in the flour and cook until flour is fully mixed in, be careful not to burn the bottom of the pot.
Whisk in the mustard powder, Worcestershire sauce, dark beer. Once that is mixed well slowly start to add your aged cheddar cheese over low heat until all of the cheese has been incorporated into the sauce.
For the Grilled cheese: Preheat the oven to 350F. Spread the beer cheese on the two inside parts of the bread. On one side layer the oven-dried tomatoes on top of the beer cheese. On the other piece of bread place the shredded Oaxaca cheese on top of the beer cheese.
Close the sandwich and spread the mayonnaise on the two outside of the bread. Place into a frying pan on low heat. Cook both sides until golden brown, then bake until the cheese has completely melted.