Heat the oil in a large saucepan over medium heat and cook the onion for 10 minutes, until soft and golden. Add the carrot and celery, and cook for 5 minutes, until just soft.
Stir in the zucchini, tomatoes, four-bean mix, chicken stock and 1 cup (250 ml) water. Add the bay leaf, oregano and lemon zest, if using. Simmer for 20 minutes, until the vegetables are tender and the chicken is cooked through.
Stir in the chopped baby spinach leaves and cook for 2 minutes, until wilted.
You can replace the four-bean mix with 2 cups cooked beans made from 2/3 cup (140 g) dried beans.
Each serving provides 1053 kJ, 252 kcal, 23 g protein, 9 g fat (2 g saturated fat), 20 g carbohydrate (10 g sugars), 6 g fibre and 1030 mg sodium.