Preheat oven to 375 degrees. Line a baking sheet with parchment paper or a silicone baking mat.
In a large bowl, combine the bread mix, oil, 2 eggs, cheese, ham, mustard, and ¼ cup water. Dump the mixture onto a clean work surface and knead until the dough is smooth. Divide the mixture into 20 equal sized balls. Place the balls on the prepared baking sheet.
Whisk the remaining egg with 1 tablespoon water. Brush the balls with the egg mixture. Combine the salt and dried onion and sprinkle on top of the balls. Bake for 18 – 20 minutes or until golden brown. Serve immediately.