Blanch the tomatoes and carefully peel them – remove any tough parts and all the seeds, reserving the juice for other uses
Puree the tomato flesh in a processor and place in a bowl
In a large heavy-bottomed saucepan, melt 3 tbsp. of the butter, add the onion and cook gently for 10 minutes, stirring frequently, until very tender but not browned
Add flour and cook gently, stirring for 1-2 minutes
Remove from the heat and pour in 1/3 of hot chicken stock and 1/2 cup of Sassy Mary Mix
Beat vigorously with a whisk until the stock has blended evenly with the mixture without forming any lumps
Pour in the remaining stock and mix well – return to a gentle heat
Add the tomato puree and stir, cover and simmer for 30 minutes, stirring occasionally
Remove from heat, beat with a hand held electric beater until well blended into a puree
Add salt, freshly ground white pepper and lemon juice to taste (optional)
