Norwegian Fish Soup with Cod (fiskesuppe med torsk)

Name: Norwegian Fish Soup with Cod (fiskesuppe med torsk)
Prep time: 10 min
Cook time: 45 min
Total time: 55 min
Cuisine: European
Ingredients: 300 g (11oz) cod fish fillets, boiled & cleaned; 2 celery sticks, chopped; 1 carrot, chopped; 1 red potato, peeled and chopped; 1 red onion, minced; 4-6 tbsp. butter; 1/2 lemon (juice needed only); 3 tbsp. tomato paste; 1 liter (0.26 gallons) water/natural fish broth; 1 tsp. coriander powder; 2 tbsp. fresh parsley, chopped; salt and black pepper to taste; 1 tbsp. hot pepper flakes (optional)