Heat the olive oil in a large pot over medium heat. Add the chopped onion, garlic, carrot, and celery. Sauté for about 5 minutes until the vegetables are softened.
Stir in the smoked paprika, cayenne pepper, thyme, salt, and black pepper, cooking for another minute until fragrant.
Pour in the seafood stock and diced tomatoes, bringing the mixture to a simmer.
Add the mixed seafood and cook for about 5-7 minutes until the seafood is cooked through.
Stir in the heavy cream and lemon juice, then simmer for an additional 5 minutes. Remove from heat and stir in the fresh parsley.
For the sesame prawn croutons, heat the sesame oil in a skillet over medium-high heat.
In a bowl, toss the shrimp with soy sauce, cornstarch, sesame seeds, salt, and pepper.
Add the shrimp to the skillet and cook for 2-3 minutes on each side until golden and cooked through.
Serve the bisque hot, topped with the sesame prawn croutons.