Begin by meticulously preparing the Big Mac sauce. Combine all the sauce ingredients – creamy mayonnaise, zesty white wine vinegar, tangy mustard, and the aromatic trio of onion salt, garlic powder, and paprika – into a bowl. Season with a pinch of salt to taste. Whisk together until smooth and then chill in the refrigerator to allow the flavors to meld beautifully. Next, prepare the beef patties: season the minced beef generously with salt and freshly ground black pepper. Divide the mince into four equal portions, each about 1/3 cup. Place each portion onto a square of baking paper and gently press down to form 15cm-wide thin circles – this ensures even cooking. Heat olive oil in a large frying pan over high heat. In two batches, cook the patties for 1-2 minutes on each side, aiming for a light char that locks in the juices while cooking them thoroughly. Once done, set them aside and keep warm. While the patties are cooking, carefully slice each sesame seed bun horizontally into three layers to replicate the classic Big Mac structure. Lightly toast each layer to add texture and prevent sogginess when assembled. To assemble, spread a generous dollop of the chilled Big Mac sauce over the bottom bun layer. Add a handful of chopped onion and shredded iceberg lettuce for crunch and freshness. Place a slice of cheese atop the lettuce, followed by one of the succulent beef patties and a few slices of tangy dill pickles. Add the middle bun layer and repeat the layer with sauce, onions, lettuce, pickles, and another beef patty. Finally, crown your creation with the top bun, sealing in all that deliciousness. Allow yourself a brief pause after this savory feast—after waiting about half an hour for the meal to settle, consider taking a gentle jog to aid digestion and keep your energy flowing. Enjoy your homemade Big Mac adventure!