Moroccan Fish Stew, New Hampshire cod style

This dish was inspired by a NY Times piece.  With the exception of chickpeas and couscous, and a few spices, the dish can be prepared using NH-local ingredients.  And, it is "wicked delicious."  By far it is one of the most flavorful soups I have ever eaten...and I fancy myself a soup snob.
You'll need to have ample soup stock on hand.  Also have the harissa at your ready (see that recipe post).
2 lbs fresh medium-firm whitefish cut into 2-inch pieces (best local choice: NH cod, pollock or haddock; Pacific halibut is a good, although obviously not local, alternative)

~3 quarts shrimp, fish, lobster or chicken stock, or combo (or water...blehh), 2-1/2 cups reserved

3 tablespoons extra virgin olive oil

1 large onion, quartered pole to pole and sliced crosswise into 1/4" pieces

1 lg (or 2 sm) leek, white/light green parts, halved lengthwise, sliced crosswise into 1/4" pieces

6 garlic cloves, minced

2 tsp cumin seeds, ground (pre-ground is fine; use about 1 tsp)

Kosher salt and freshly ground pepper to taste

28 oz (typical large can) good quality stewed plum tomatoes, with liquid

2 Tbsp tomato paste dissolved in 1/2 cup water

1/4 to 1/2 tsp cayenne, optional, to taste

1 lb carrots, cut in 1/4" slices (fat ends first cut in half lengthwise)

1/2 lb turnip, peeled and cut into large dice

1 can chickpeas, drained and rinsed

2 Tbsp harissa, plus additional for serving

1 cup chopped flat-leaf parsley or cilantro, or 1/2 cup of each (I used both, and generously)

2-2/3 cups couscous, prepared using reserved stock

1. Bring stock to simmer in its own pot.

2. Heat olive oil over med heat in large Dutch oven. Add onion and leeks. Cook, stirring, until tender, about 5 minutes, then stir in garlic, ground cumin seeds, and 1/2 tsp salt. Cook, stirring, until fragrant, about a minute.

3. Add tomatoes to leek mixture. Cook down--mixture will be very fragrant--about 10 minutes. Stir in dissolved tomato paste, cayenne, harissa, stock (minus reserved amount for couscous), carrots, turnips, and chick peas and bring to light boil. Cover, reduce heat to simmer, and cook 30 minutes. Taste/adjust seasonings.
4. Make the couscous according to package directions using the reserved stock.

5. Cut fish into lg chunks. Season lightly w/ s & p, then add to simmering stew, along with parsley/cilantro. Stir gently and simmer for ~4-5 minutes, until the fish is opaque. Taste/adjust seasonings.

6. Fluff couscous.  Add a scoop to each serving bowl.  Ladle in fish and veggies with plenty of broth. Garnish w/ cilantro leaves.  Serve with harissa.

Original recipe here.