1) In a saucepan, melt butter, add onions, saute until translucent.
2) Add tomatoes, salt, pepper, baking soda, thyme
3) Bring to boil, reduce heat and simmer about 15 min.
4) Puree in a food processor or blender. Strain through a sieve or food mill.
5) Return to saucepan and stir in orange juice and cream