For the turkey patties: In a large bowl, combine the turkey, ricotta, sage, soy sauce, Worcestershire sauce, Dijon and sprinkle with some salt and pepper. Divide into 4 equal patties and press them into 1/4-inch-thin rounds.
Heat a cast-iron griddle pan to medium-high heat.
Add the canola oil and sear the patties on the first side until golden brown, 3 to 4 minutes. Flip and cook for another 3 to 4 minutes until cooked through.
For the sandwich build: Place a slice of Swiss cheese on each piece of bread, then a turkey burger, followed by about 1/4 cup Caramelized Onions. Place the top piece of bread on and then butter each side of the sandwich.
Griddle each side over medium heat until golden, 2 to 3 minutes on each side. If you have a metal bowl, cover the sandwiches so they steam a bit and the cheese will melt faster. Serve with good ol' yellow mustard if you like and a big pile of oven fries.
Heat a large heavy-bottomed pot over medium-high heat. Add the butter and olive oil, let the butter mel,t and then add in the onions and toss to coat. Sprinkle with salt and pepper, and then cover the pot and lower the heat to medium-low.
Let the onions sweat, steam and soften for 10 to 15 minutes. Uncover the pan and let the onions cook for about an hour, checking on the onions frequently and stirring.
Once the onions are fully caramelized, and a deep golden color, add the sherry and scrape up any bits from the bottom of the pan. Stir in the thyme, season with salt and pepper and set aside.