Tip the bean mix into a sieve, wash under running water, then shake the sieve to remove excess water.
Put the olive oil in a medium saucepan over medium low heat. Add the onion, stir through to coat with the oil. Put the lid on and sweat the onion until transparent, stirring just occasionally.
Add the garlic, stir through and cook for another 30 secs.
Add the bean mix and stir through, leaving it to heat for 30 secs.
Add the tomato paste, the mixed herbs, the red wine vinegar and the chicken stock. Stir through and turn up the heat to a gentle simmer. Cook for 15 mins with the lid on. If the liquid dries out, top up with a little hot water.
A few minutes before serving, add salt and black pepper to taste and stir through.