Place the cilantro, parsley, 2 minced garlic cloves, 2 tablespoons olive oil, lemon juice, cumin, paprika, and coriander in a food processor. Pulse until a rough paste forms.
Toss the monkfish pieces with half the chermoula paste and set aside while you prepare the vegetables.
Heat the remaining tablespoon of olive oil in a large pot over medium heat. Add the onion and remaining 2 minced garlic cloves and cook until the onion softens.
Add the carrots, parsnips, and sweet potato to the pot. Stir in the diced tomatoes and vegetable broth.
Bring the mixture to a simmer and cook for 15 minutes until the root vegetables are just tender.
Add the marinated monkfish and the remaining chermoula paste to the pot. Simmer gently for 6 to 8 minutes until the fish is opaque and flakes easily.
Season with salt and black pepper to taste before serving.