Holiday Burger

This burger is a perfect way to use up holiday left-overs!

Burger patties:
3/4 cups lentils + 1 1/2 cups water
1 medium carrot
1 stalk celery
8 button mushrooms
1 tbsp fresh sage
1 tsp fresh thyme
1/4 cup onions
1 flax egg (1 tbsp ground flax + 3 tbsp water)
1/3 cup oats 

Gravy:
1 1/2 cups vegetable stock
1 tbsp tahini
1/4 cup soy sauce
dried herbs like thyme, oregano, sage, black pepper
1 tbsp nutritional yeast
drizzle maple syrup