First get your veg pickling. Place the celery, cucumber, raisins and eschalots in a large bowl. In a jug combine the vinegar, water and sugar, mix well until dissolved and pour over the veg. Set aside to pickle for at least 45 minutes.
My mackerel is just a cheats, quick smoke version, however, I actually prefer the subtlety for a dish like this. First, get your BBQ on, I usually do it in the Weber. Get the BBQ hot, add wood over on the grill over the flame and leave, BBQ closed, for the wood to start burning. Next, oil and salt the mackerel skin. Once the wood is burning and smoking, place your fish, skin side down on the grill. I like to do that with this so the skin goes charred and crisp, which give another dimension to the dish. Cook the fish with the lid closed for about 6 minutes, depending of the size and shape of the fillet. You want it just cooked, not dried out. Once cooked, place on a plate and loosely cover with foil to keep warm.
Then you can toast your bread, either in a toaster or even on the BBQ grill. Then assemble. Add your celery and parsley leaves to the pickled salad and give it one last toss. Smother your toast generously with aioli, place a good amount of pickled veg, add your mackerel, either broken up and scattered around or on top in one piece. Then, eat. So yummy. Crunchy, creamy, zingy, smokey, fishy. Yum.
Recipe by Eatin' mess at https://eatinmess.com.au/recipes/by-ingredient/seafood/smoked-mackerel-toast-with-pickled-salad/