“an old desiccated ruin of dust-laden bread and mummified ham or cheese”. I doubt there was a recipe, by the sounds of it. Start with bread that sounds like a 2x4 when you strike it against the table, add fuzzy cheese, maybe a slice of over-aged sandwich meat, skip the mayo, that will just smell foul (fowl? Because it’s made of eggs?) add some sauerkraut, just to make sure it smells kinda funky, and bam! You got a soup going… no, wait, that’s a sandwich.