Grilled Mackerel with Stewed Tomatoes, Pesto and Onions

Here we are looking at simple ingredients, and we all know that tomatoes, onions, garlic and basil work well together. I have added the slight Italian influence, using pesto sauce. This has so many uses: as a seasoning, a sauce on its own, or to flavour cream sauces or tomatoes. It can be made at home, but good pesto can be found in almost any supermarket or delicatessen.

I use the mackerel as a starter and so only serve one fillet a portion, but like most dishes this would also mak