Yes to sourdough. Must be white. Must have a good crust (defence barrier to avoid losing melted cheese).
Salted butter inside.
Thick slice of cheese. Leave about half an inch perimeter, don’t want to waste any melted cheese.
Make sandwich.
Salted butter on both outsides.
Put in frying pan or griddle pan.
Yes to lid of cast iron casserole dish on top. Anything heavy and flat will do.
Medium heat.
Flip once and only once.
Dip into home made tomato soup, which you have made by roasting tomatoes, garlic and salt and pepper, blitzing in a Nutribullet or whatever, adding a dash of balsamic vinegar/sugar (depending on how sweet or sour your tomatoes were) and then heated through in a pot with chicken broth. Sprinkle basil leaves on top.
Grilled cheese sandwiches must be cut in suitable size and shape for the bowl soup will be served in obvs.
It’s basically a margherita pizza, but different ratio of ingredients and a million more kg of animal fat.