Low-carb bangers and mash

Chop two leeks
Chop one cauliflower and steam until soft
Crush three cloves of garlic
Melt some butter in a pan, cook the garlic then add the leeks and a glug of white wine vinegar
Add one tablespoon of mustard
Simmer until very soft
Add cauliflower to the leeks
Pop it in a food processor until smooth
Add salt, white pepper, grated parmesan and one tablespoon of sour cream
Whisk until smooth