PreparationMake the Salsa: Mix onion, bell pepper, and tomato in a large bowl. Add oil, vinegar, and lemon juice, then toss to combine. Taste and season with salt and pepper, then toss again. Do Ahead: Salsa can be made 5 days ahead. Transfer to a jar or airtight container and chill. Let sit at room temperature at least 30 minutes before using. Make the Hot Dogs: Slice sausages in half lengthwise, going almost all the way through so they can be opened like a book, but are still attached on one side. Heat a large nonstick skillet over medium-high until hot. Working in batches, cook sausages cut side down, weighting down with a spatula or a small pot lid and turning once, until slightly browned, about 2 minutes per side. Transfer to a plate. Smear a generous amount of mayonnaise on both sides of buns. Arrange 2 butterflied hot dogs on each side of buns, cut side facing the bread. Top with mustard and a generous amount of salsa.
PreparationMake the Salsa: Mix onion, bell pepper, and tomato in a large bowl. Add oil, vinegar, and lemon juice, then toss to combine. Taste and season with salt and pepper, then toss again. Do Ahead: Salsa can be made 5 days ahead. Transfer to a jar or airtight container and chill. Let sit at room temperature at least 30 minutes before using. Make the Hot Dogs: Slice sausages in half lengthwise, going almost all the way through so they can be opened like a book, but are still attached on one side. Heat a large nonstick skillet over medium-high until hot. Working in batches, cook sausages cut side down, weighting down with a spatula or a small pot lid and turning once, until slightly browned, about 2 minutes per side. Transfer to a plate. Smear a generous amount of mayonnaise on both sides of buns. Arrange 2 butterflied hot dogs on each side of buns, cut side facing the bread. Top with mustard and a generous amount of salsa.