For the beans, place a heavy-bottomed saucepan onto a medium heat and add the olive oil, shallots, thyme leaves, bay leaf, garlic, ginger and peppercorns. Gently fry for 2-3 minutes, until the shallots are soft but not coloured.
Add the vinegar to the pan and swirl to combine. Remove from the heat and allow to cool.
Meanwhile, bring a pan of lightly salted water to the boil and blanch the beans for two minutes. Drain and refresh the beans in cold water.
Place the beans into a large bowl and sprinkle with the sugar, tossing gently to coat. Pour the cooled vinegar mixture over the beans and set aside.
For the jacket potatoes, preheat the oven to 200C/400F/Gas 6.
Pierce the baking potatoes several times all over with a sharp knife, then place into the oven to bake for one hour, or until crisp on the outside, but tender when pierced with a knife. Remove from the oven and allow to cool slightly.
Preheat the grill to its highest setting.
Meanwhile, heat a frying pan until hot. Add the bacon strips and fry, stirring occasionally for 3-4 minutes until golden and crisp. Remove the bacon from the fat with a slotted spoon and set aside to drain on kitchen paper.
When the potatoes are cool, place them onto a board and slice the tops off. Using a spoon, scoop out all of the potato flesh from the skins and place the flesh into a clean bowl.
Mash the potato flesh until smooth, then add the cooked bacon, flaked mackerel and crème fraîche. Season, to taste, with salt and freshly ground black pepper.
Carefully spoon the potato mixture back into the potato skins and place onto a baking sheet. Top each potato with a piece of Taleggio and place under the grill to cook until the cheese is golden and bubbling.
To serve, place the jacket potatoes onto four plates and place a spoonful of the pickled beans alongside.