Russian Salmon Soup Ukha

Name: Russian Salmon Soup (Ukha)
Ingredients: 1⁄4 cup extra-virgin olive oil; 4 small carrots (1 chopped, 3 thinly sliced); 8 black peppercorns; 4 sprigs flat-leaf parsley; 4 sprigs dill; 2 leeks (white parts only), thickly sliced crosswise and washed; 2 ribs celery, roughly chopped; 2 bay leaves; 1⁄2 tsp. crushed red pepper flakes; 1 1⁄2 cups white wine; 1 lb. fish bones, such as snapper, rinsed; 1 salmon head (about 1 lb.), gills removed; 3 medium yukon gold potatoes, peeled and cut into 1⁄4″ chunks; 1 lb. skinless boneless salmon filet, cut into 1″ cubes; 1 tbsp. fresh lemon juice; Kosher salt and freshly ground black pepper, to taste; 4 scallions, thinly sliced on the diagonal