Heat butter and oil in a large saucepan over medium heat. Add the onion, leek and carrot and a big pinch of salt. Cook, stirring often, for 5 minutes or until vegetables have softened but not coloured. Add the garlic and bouqet garni Season with salt and pepper. Cook stirring for 1 minute.
Pour in the chicken stock and bring gently to the boil. Add the chicken thighs and return to a gentle boil. Once boiling, cover partially with a lid, reduce heat and simmer gently for 20 min or until chicken is cooked through. Reduce heat to low.
Carefully remove chicken thighs with tongs and transfer to a plate. Allow to cool for a few minutes before shredding the chicken or cutting into bite size pieces.
Return the chicken to the pot and add the peas, zucchini and lemon zest. Cook for a further 2 minutes or until the peas and zucchini turn bright green and just tender. Season to taste. To serve, divide quinoa (or other grain or pasta) among bowls and ladle over the soup. Garnish with chopped fresh parsley. Serve with fresh crunchy bread or toast of your choice.