One thing I make I call my version of ratatouille.Chop up a good selection of veg, Saute in olive or rapeseed oil, add a handful of raisins & a couple of dried apricots, chopped.
Add some paprika & cumin, chicken or veg stock.( I use stock powder) also a splash Balsamic vinegar.
Add a tin chopped tomatoes & 1 tsp sugar ( the toms. need a little sugar)
I don't add water because I like this really thick.
Cook slowly for 45mins -1 hour.
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Have you tried cooking your sm. mackerel in orange & lemon juice in the microwave for a couple of mins? Serve with new potatoes and selection of veg. steamed.