In a large pot heat up the oil, add the garlic, ginger, chilli and onion, and gently cook for 2-3 minutes stirring occasionally.
Add the lentils, stir and cook for 2 more minutes.
Add the tomatoes, coconut milk, tarragon and salt, stir, cover, bring to the boil, then simmer for 15 minutes, stirring often (don't let the lentils stick to the bottom of the pot).
Add the fish, stir carefully, cover and cook for 2 minutes. Turn off the heat and leave to stand, covered, for about 3 more minutes. Serve with rice or quinoa (ensure the fish is cooked through).
Herbs: I think tarragon goes extremely well with fish. I've used it before in my Spicy Fish Wraps recipe as well as Fish Pie with Avocado and Tarragon. It is so fragrant and really complements the coconut and ginger in the stew. However, either thai basil or cilantro would work well too.
You can use any white fish to make this easy stew recipe, so just use whatever is easiest to get where you live. (I used cod but haddock, pollock or hake would be fine too). Frozen fish is fine too, but let it thaw completely first. You can refrigerate it overnight to defrost slowly.
Use similar size fish pieces so they cook evenly.
As fish cooks very quickly it gets added to the stew in the last 2 minutes of cooking. After you've turned off the heat let it stand, covered, for about 3 more minutes before serving. Overcooking the fish might make it tough and stringy, but do ensure it is cooked through before you serve it.
Refrigerate for up to 3 days.
Freeze individual portions in airtight containers for up to 3 months (do not freeze if your fish had previously been frozen).