Preheat the griddle to medium heat for a few minutes. Add some cooking oil, the potatoes, kosher salt, pepper, and some water. Cover with a melting dome and cook 6 to 7 minutes. Remove the dome a few times to flip the potatoes and add more water each time before covering again.
Set the melting dome aside and add more cooking oil, the chicken, jalapenos, dry ranch seasoning, more kosher salt, and pepper. Cook together 6 to 7 more minutes, mixing with hibachi spatulas a few times.
Add the garlic and cook another 2 to 3 minutes. Serve with ranch dressing for dipping if desired.