a bowl, not a mug. We have some of those spoons that have substantially more capacity than a traditional Western spoon. Your complaint is ultimately with the inferiority of the Western spoon, which simply lacks the capacity necessary to efficiently deliver a whole bowl of soup in a timely manner. But there is even Eastern precedent for your strategy, as my wife makes miso soup everyday for herself (neither I nor my son want to consume that much soy) and she has a more refined small bowl that she drinks it from after eating the tofu and seaweed with chopsticks.

You're totally fine on the mug concept here, but there are bisques and chowders that I think possess a richness that does warrant the use of a spoon and don't need to be poured straight down the gullet.