Melt the butter and oil in a large skillet over medium-high heat. Add the onions and sweat until softened. Add the celery, pepper, and garlic. Cook for 2 minutes. Mix in the old bay, cayenne, paprika, allspice, pepper, and oregano. Add the tomato and stock. Allow the liquid to reduce and add the shrimp, green onion, and parsley. Cook until the shrimp turn pink and remove from heat. Add the lemon juice and season with salt. Cool completely before filling the pies.