Peel and finely chop the onion and carrot. Cut the courgette into small pieces. Trim and finely slice the runner beans. Peel and grate the garlic.
Separate the chard leaves and stalks. Finely slice the stalks and roughly chop the leaves.
Pour 1 tbsp oil into a large pan and bring to a medium heat. Add the lardons and fry for 3-4 mins, turning occasionally, until golden on all sides.
Slide in the garlic, carrot, onion, chard stalks and courgette along with a pinch of salt and pepper. Cook for a further 5 mins, stirring occasionally.
Tip the barley into the pan and top up with 1 ltr boiling water. Crumble in the stock cube and stir well. Bring to the boil, then reduce to a simmer, cover with a lid and cook gently for 20 mins.
Add the runner beans and chard leaves and stir well. Cook for 2 mins.
Roughly chop the basil and mint leaves and stir most of them through the soup. Grate the zest of the lemon in.
Ladle the minestrone into bowls, topping with the remaining herbs and a dollop of creme fraiche. Serve with wedges of the lemon.