For the relish, heat the oil in a frying pan and cook the chopped ingredients over a low heat for 15 minutes. Add the sherry vinegar and sugar and cook for a few minutes until glossy. Add 50ml/2fl oz water and continue to cook until the vegetables are tender.
Transfer to a food processor and blend to a smooth purée. Set aside until ready to serve.
For the skordalia, place the potatoes in a heavy-based pan with the garlic, milk and olive oil, and season to taste with salt and pepper. Place over a medium heat, bring to the boil and cook for 15-20 minutes, or until the potatoes are soft.
Remove from the heat and drain the potatoes, reserving the cooking liquor. Place the potatoes in a food processor and blend with the lemon juice and half of the cooking liquid. Return to the saucepan and fold in the parsley.
For the venison cutlets, put the flour in a bowl and season generously with salt and pepper. Spread the breadcrumbs on a plate and mix in the chopped herbs.
Place the beaten egg in a shallow bowl. Place the flour, beaten egg and breadcrumbs in a line ready for coating the cutlets. Roll the venison cutlets in the flour (including the bone), dip in the egg and coat with the breadcrumbs. Make sure the cutlets are evenly coated all over and the crumbs patted down (to help them stick to the cutlets).
Preheat the oven to 150C/300F/Gas 2.
Set a large heavy-based pan over a medium heat. Add two tablespoons of oil and, once the oil is hot, add the cutlets (you should fit six in a pan, but cook in smaller batches if necessary). Fry for 2-3 minutes each side, or until golden-brown and cooked to your liking. Once cooked place in the oven to keep warm while you cook the remaining cutlets.
To serve, reheat the skordalia and, when warm, divide among serving plates. Place three cutlets on top and serve with a quenelle of relish.