Masala Omelet Sandwich

Name: Masala Omelet Sandwich
Ingredients: 2 tablespoons milk; 1 tablespoon chopped fresh cilantro; 1/2 teaspoon kosher salt; 1/2 teaspoon cracked black peppercorn; 1/4 teaspoon garam masala; 1/4 teaspoon turmeric powder; 1/8 teaspoon red chile powder; 3 large eggs; 1 tablespoon salted butter, preferably Amul; 1/2 teaspoon cumin seeds; 2 tablespoons finely chopped red onions; 1 tablespoon finely chopped tomatoes; 1/2 teaspoon finely chopped green chiles; 1 teaspoon finely chopped ginger; 2 slices sourdough bread; 1/4 cup grated processed cheese, such as Amul cheese (or white Cheddar); Hot and sweet ketchup, such as Maggi, for serving