Stir in the stock and season with salt and pepper.
Then stir in the yogurt, and season with pepper.
When vegetables have softened, stir in the tomatoes and season.
Just before serving, stir in the butter and season to taste with salt.
Stir in the grapefruit juice and season with sea salt.
Stir in the lemon juice and season with salt to taste.
Stir in red peppers and season with black pepper.
Stir in the capers and season with red pepper flakes.
Stir in the cream, season with Tabasco, and cook for about 2 minutes.
At end of cooking, stir in butter, and season to taste with black pepper.