Place a large stockpot over medium heat. Add the margarine and stir until melted. Add the onion, carrot, celery and garlic and cook for 10 minutes, stirring frequently. Sprinkle the flour over the vegetables and continue cooking and stirring until the flour browns slightly, about 2 minutes.
Add the stock, tomatoes with their juices, parsley, thyme and bay leaf. Increase the heat to high and bring to a boil. Then reduce the heat to medium low and simmer for 30 minutes. Season with salt and pepper to taste. Stir in the Cashew Cream and continue to simmer for 10 minutes, taking care not to let the soup boil. Remove and discard the bay leaf.
Working in batches, pour the soup into a blender or food processor and blend on high for several minutes, until very smooth. Ladle into bowls and serve.
Put the cashews in a bowl and add cold water to cover them. Cover with a lid or plastic wrap and refrigerate overnight.
The next day, drain the cashews and rinse under cold water. Put them in a blender with enough fresh cold water just to cover them. Blend on high for several minutes until smooth. Strain the cream through a fine-mesh sieve to remove any remaining bits of cashew. Store refrigerated for 2 weeks or in the freezer for up to 3 months.
When blending hot liquids, first let cool for 5 minutes or so, then transfer to a blender, filling only halfway. Put the lid on, leaving one corner open; this will prevent the vacuum effect that creates heat explosions. Cover the lid with a kitchen towel to catch splatters and pulse until smooth.
Adapted from "Trisha's Table: My Feel-Good Favorites for a Balanced Life" by Trisha Yearwood (c) Clarkson Potter 2015. Provided courtesy of Trisha Yearwood. All rights reserved.