Mix the sweet chili sauce
Add the rice vinegar, sugar, garlic, ¼ cup of water and red pepper flakes to a small pot. Bring to a boil then reduce to a simmer, stirring until the sugar dissolves. Simmer until the mixture reduces slightly, about 6 minutes.
Thicken the sauce
In a bowl whisk together cornstarch and of cold water. Add the slurry to the sugar mixture, whisking to combine. Continue to simmer until thick and shiny, Remove and cool.
Sauté onion and peppers
Heat a large cast iron pan or large skillet over medium high heat, add olive oil and heat. Add the onion and jalapeño and sauté, stirring occasionally until the onion is tender, about 5 min.
Add the roast beef
Add the roast beef and top with Worcestershire followed by slices of American cheese. Turn the heat to medium low and allow the cheese to melt.
Melt the cheese
Once the cheese melts use a metal spatula to mix it up with the beef, using the spatula to chop the beef into smaller pieces. Season with salt and pepper. Remove to a mixing bowl and let the filling cool to the touch.
Fill the egg rolls
Fill a small bowl with just a little water. Scoop about 3 tablespoons of the filling and drop just below the center of the egg roll wrapper.
Fold the egg rolls
Pull the bottom corner up and fold each side in and continue to tightly roll the wrapper. Dip one finger in water and spread around the edge of the wrapper to seal it. Set aside and continue with the remaining wrappers and filling.
Fry egg rolls
Add enough oil to reach 2-inches up the side of a cast iron skillet. Heat the oil to 350ºF. Work in batches and add egg rolls and fry until golden brown on all sides, about 2 to 3 min. Remove to a paper towel-lined plate to drain. Repeat with the remaining egg rolls.
Drain egg rolls
Remove to a paper towel-lined plate or rack set over a baking sheet to drain. Repeat with the remaining egg rolls.
Cut the egg rolls in half diagonally and garnish with chives. Serve hot with the chili dipping sauce on the side.