1Simmer diced tomatoes in juice in a saucepan over low heat until hot, 7 to 10 minutes. Add baking soda and let the mixture foam. Stir tomato soup, parsley, sugar, margarine, chicken base, and white pepper into the tomato mixture; cook until hot, about 5 minutes. Pour milk into tomato mixture and stir; cook until hot, about 5 minutes.