- 1 (7 ounce) can whole fire-roasted mild green chiles (such as La Victoria®), or more to taste, diced
- 1/2 cup dried minced onion
- 1/3 cup prepared yellow mustard
- 1/3 cup butter, softened
- 2 tablespoons poppy seeds
- 8 hamburger buns, split
- 16 slices deli ham
- 8 slices Swiss cheese
- Preheat oven to 350 degrees F (175 degrees C).
- Mix green chiles, onion, mustard, butter, and poppy seeds together in a bowl; spread about 1 tablespoon onto each cut side of each hamburger bun. Layer two pieces of ham around each slice of Swiss cheese and place onto the bottom halves of the buns, sandwiching the meat and cheese with the top halves.
- Wrap each sandwich in aluminum foil.
- Bake sandwiches until the cheese is melted, 6 to 10 minutes.