In a Dutch oven over medium heat, fill halfway with canola oil and bring to 375 degrees F.
In a mixing bowl, whisk together the flour, beer, salt and 1/2 cup water until combined. The consistency should be pourable, but thick enough to coat your onion rings. Add extra beer if needed to thin it out. Dunk each segment of the cut onion into the batter, letting the excess batter drip off. Carefully add the battered onions to the hot oil, frying in batches, being careful not to overcrowd the Dutch oven. Fry until golden, 3 to 4 minutes. Repeat with the remaining onion rings. Drain on a paper-towel-lined plate and set aside. Season immediately with a sprinkle of salt.
Dunk each chicken tender in the same batter, letting the excess batter drip off. Carefully fry in batches until golden, about 8 minutes. While the chicken is still hot, toss with the wing sauce combined with the melted butter in a bowl.
On a slice of bread, place 2 pieces crispy chicken, 3 large onion rings and top with some of the Zesty Blue Cheese Slaw. Top with second slice of bread. Repeat for the remaining sandwiches and eat like an animal.
Zesty Blue Cheese Slaw:
Combine the blue cheese, mayonnaise, buttermilk, vinegar, honey and mustard in a bowl. Whisk to combine, then mix in the carrots, green cabbage and red cabbage. Adjust the seasoning if necessary and let sit in the fridge for at least 30 minutes.