Warm up olive oil in a big pot on medium heat.
Cook chopped onion, celery, and carrot in a pan until they are soft, for around 5 minutes.
Put garlic in the pan and cook for one more minute.
Add tomato paste, paprika, cayenne (if desired), and season with salt and pepper.
Cook for 2 minutes, stirring all the time.
Put flour on top of the mixture and mix well.
Cook for one more minute.
Slowly pour in the broth while stirring constantly to avoid clumps.
Cook gently over low heat for 10 minutes, stirring from time to time.
Blend the soup until it is smooth using a hand blender, or pour it into a regular blender in small amounts.
Add the heavy cream and let it cook for 10 more minutes until it thickens a bit.
Include crab meat, shrimp, and sherry (if desired).
Cook for 5 minutes or until the seafood is warm, making sure to keep the heat low to prevent the cream from curdling.
Add salt and black pepper to taste.
Serve the dish hot and add fresh herbs on top.
