A bowl of this stew is like a tiny little trip to the Mediterranean. It’s unbelievably easy, but I would serve it to guests in a heartbeat (and it would be a pretty special Mother’s Day lunch or dinner). It’s hearty, but still so light and clean and simple.
The saffron is optional, mostly because of cost. Saffron is a wonderful but pricy spice; it’s made from the stamens of crocuses, which might not sound delicious, but it adds a flavor that is at once elusive, aromatic and deep. And a little goes a long way — just a pinch of saffron adds so much dimension to the soup.
You can absolutely positively serve the stew as is, with no extra adornment besides the shredded basil. Traditionally, in the south of France, this type of fish stew or soup is served with rouille, a bread-thickened sauce featuring peppers and seasonings. It’s usually also accompanied by bread, and the sauce can be dolloped on the bread, and then floated in the stew so the sauce swirls into the liquid. As an unconventional but practical shortcut, you can stir a little bit of harissa or other chili paste into a mixture of sour cream and mayonnaise for a spicy-creamy approximation of rouille.
But truly, once the fragrance of this stew, both warmly and brightly flavored, rises from the bowl, the only accompaniment you’ll be looking for is a spoon.