Chicken Mince Toasted Sandwich

Name: Chicken Mince Toasted Sandwich
Ingredients: 4 Bread Slices; As needed Butter; For Marinating the Chicken Mince:; 450 gms Chicken Mince; 2 tbsp Ginger Garlic Paste; 2 tbsp Lemon Juice; 1/4 tsp Turmeric Powder; As required Salt; 1 tsp Fennel Powder; 1 tsp Black Pepper Powder; 1 tsp White Pepper Powder; 1 tsp Cumin Powder; 1 tbsp Chicken Masala/Garam Masala; For Cooking the Chicken Mince:; 2 tbsp Oil; Pinch Asafoetida; 2 Onions (Chopped); 5-6 Green Chillies (Finely Chopped); 1 sprig Curry Leaves; 2 tbsp Coriander Leaves (Finely Chopped)