Japanese Dark Seafood Curry

Name: Japanese Dark Seafood Curry
Prep time: 20 min
Cook time: 50 min
Total time: 1 h 10 min
Cuisine: Japanese
Ingredients: 100 g tuna; 3 tbsp soy sauce (to marinate); 1 yellow onion (thinly sliced); 1 tbsp olive oil (for caramelized onions); 10 large shrimp (shells on); 2 pinches salt (for cleaning); 1 tsp cornstarch (for cleaning); 2 tbsp olive oil (for shrimp oil); 100 g scallops (or mixed seafood); 2 potatoes (medium, peeled and roughly cut into bitesize pieces); 1 carrot (peeled and roughly cut into bitesize pieces); 2 tbsp unsalted butter; 3 cloves garlic (minced); 1 tbsp ginger (minced); 2 ½ tbsp curry powder; 3 tbsp flour (all purpose or cake flour); 1 tsp squid ink (optional); 850 ml dashi stock; 1 bay leaf; 2 tbsp white wine; ½ tsp garam masala; ½ tsp coffee powder; ½ tbsp honey; ½ tbsp blueberry jam; ½ tbsp Worcestershire sauce