Method
Season the mackerel fillets with a little salt and pepper. Dust them generously with flour, then dip each fillet into the egg, followed by the oats. Make sure they have a nice, even coating.
Set a medium, deep frying pan down over a hot fire and add the extra-virgin olive oil. Lay the bacon slices down in the pan and fry them for a few minutes on each side, until their fat begins to render and they’re beginning to crisp. Lift the bacon out of the pan and set aside for a moment.
Add the butter to the hot pan, followed by the coated mackerel fillets. Fry them for 3–4 minutes on each side, or until their oaty coating is golden and crisp. Lift the mackerel out of the pan and set them to one side with the bacon. Now scatter in the gooseberries and the thyme leaves (if using) and give them a shake about the pan. After about a minute of cooking, add the sugar and a couple of tablespoons of water and continue to cook for 30 seconds or so, shaking the pan as you go. Just as the gooseberries are beginning to soften and split, return the bacon and the fish to the pan, warm through and serve.