French Onion Soup

Melt butter in a heavy based casserole pot over medium heat. When it starts to foam, add onions and stir to coat in butter.

30 min on medium low: Turn heat down to medium low. Cook for 30 minutes stirring every few minutes, until the onions have softened and are semi transparent.

Salt, 20 min on medium high: Turn heat up to medium or medium high. Add salt, and cook for a further 20 - 30 minutes, stirring more regularly, until onions are deep golden and sweet.