In a nonreactive saucepot, combine the tomatoes with the broth bouquet Garni and bring to a simmer. Cook covered over low heat for 15 minutes. Remove bouquet Garni from the soup and pass it through a sieve. Return the sieved mixture to the saucepan and whisk in the tomato paste; simmer until heated through or boil down until the desired consistency. Season to taste with salt and pepper and garnish with sour cream and chives if you wish.