In a bowl, combine meat with herbs, mustard, salt and pepper, and form 4 large patties.
Heat non-stick skillet with EVOO over medium-high heat. Cook burgers 6-7minutes on each side until firm and cooked through.
Meanwhile, heat a small saucepot over medium heat and melt the butter. Add shallots, carrots, celery, salt and pepper and sauté 7-8 minutes to soften. Sprinkle with flour, stir 1 minute then whisk in broth. Let thicken 3-4 minutes then stir in peas and heat through.
Top each toasted muffin bottom with a burger and some pot pie gravy. Replace the muffin tops and serve.