Gently fry the onion and garlic in the margarine for a few minutes until golden. Add the flour, chicken and mushrooms. Fry for 3 minutes or until the chicken is lightly browned.
Add all the other ingredients except the lemon juice and salt. Cover and simmer for 30 minutes, or until the chicken thighs are thoroughly cooked (check by piercing with a skewer – the juices should run clear).
Add lemon juice and salt to taste. Serve with rice.