In a small bowl, whisk together all sauce ingredients until smooth. Chill while you prep the tacos.

Heat an electric griddle to 400℉ or a dry cast-iron skillet over high heat until very hot. If using stainless steel, add 1 tbsp oil and swirl to coat.

Divide and gently form cold beef into six 2-1/2-ounce balls.

Press each beef ball onto one side of a tortilla as thin and evenly as possible. Season with salt and pepper. Place the tortilla beef-side down on the hot griddle. Immediately press with a burger press or small pan for 5 seconds to set the crust. Sear for 2 to 3 minutes until edges are deeply browned.

Use a stiff metal spatula to release the beef from the pan. Flip so the tortilla side touches the heat. Quickly top with a slice of cheese and cover with a lid or metal bowl for about 1 minute, until cheese is melted and the tortilla is golden and crisp.

Fold gently and transfer to a plate. Top with your favorite toppings and a generous spoonful of sauce. Serve immediately.

To batch cook, place finished tacos on a wire rack in a 200°F oven until ready to serve.