To make the Venison: Preheat the oven to 350 degrees F.
Rub the venison with salt and pepper. Heat the oil in an oven-proof large skillet over high heat. Sear the venison on all sides until golden brown. Transfer the venison to the oven and roast for 30 to 40 minutes, until the internal temperature of 125 to 130 degrees F. Remove from the oven and let rest, about 10 to 15 minutes. Cut the venison into thin slices.
To make the Remoulade: Finely chop the pickled vegetables and transfer to a bowl. Add the mayonnaise and curry powder and mix. Season with salt and pepper, to taste.
To make Fried Onion Rings: Pour the oil for frying into large pot to depth of 2 inches and heat to 375 degrees F. In a bowl, toss the onion rings with the flour. Working in batches, fry the onion rings until crispy. Using a slotted spoon, transfer the onion rings to paper towel-lined plate and season generously with salt.
To serve, spread the bread slices with the remoulade and top with the venison and onion rings.