In a medium bowl, mix the ground beef, soy sauce, Chinese ve-spice powder and 1/2 tsp. salt. Shape into four 6-inchlong, hot dog-shaped logs; carefully push a metal skewer through the center of each burger dog. Transfer to a plate and refrigerate 30 minutes.
In a small bowl, whisk the mayonnaise and hoisin; season. Cover and refrigerate.
In a small saucepan, heat the oil over medium until a deep-fry thermometer registers 225 degrees. Pat the onions dry. In a bowl, toss the onions and flour.
Working in two batches and using a slotted spoon, gently lower the onions into the oil. Fry, stirring often, until golden brown, 5 to 7 minutes per batch. Transfer to paper towels to drain; season with salt.
Heat a grill or grill pan over medium-high. Brush the buns with oil and cook, cut sides down, until golden brown. Transfer to a plate. Add the burger dogs to the grill or grill pan; cook, turning occasionally, 8 to 10 minutes for medium.
Place the burger dogs on the buns and pull out the skewers. Top with the hoisin mayo, crispy onions and pickled cherry peppers.