Add the onion and ginger garlic paste and cook till wilted.
Add the mince meat with some salt and cook till it turns whitish. Break down with a spatula as you stir it.
Add the masala powders and the tomato paste and mix well. Sprinkle some water if too dry. Cook till done. Adjust seasoning, add the coriander leaves and switch off. Allow to cool.
For making toasties, spread a thin layer of mayonnaise or cheese on both toasts, fill with enough filling. Toast in your sandwich maker. Enjoy hot.
Notes
I usually don't use any oil or butter while toasting my bread. You may use as required.