Begin by warming your shredded birria and birria consommé in two small saucepans over low heat for about 5-7 minutes until heated through and hot.

While the birria and consommé warm, shred the Oaxaca cheese into a bowl. If using red onion and cilantro, chop them finely and set aside.

Butter one side of each slice of sourdough bread. On the unbuttered side, layer cheese, birria, and more cheese, then top with another slice of bread, buttered side up.

Heat a skillet over medium heat and grill sandwiches for 3-5 minutes per side until golden brown and crispy, and cheese is melted.

Carefully remove the sandwiches from the skillet, let them cool for a moment, then slice diagonally. Serve with birria consommé for dipping and garnish with cilantro and red onion if desired.