For green beans a la grecque, clean, wash and halve the beans lengthwise. Mix the tomato paste, 3/8 l water, olive oil, onion and garlic.
Put the beans in a pot and pour the tomato mixture over them. Season with salt and pepper.
Bring everything to a boil and simmer over low heat, stirring occasionally, for about 45 minutes without a lid until the beans are tender.