Add all ingredients to a bowl and stir until well combined. Set aside.
For the Cornish game hens and vegetables:
Heat the oven to 375 degrees F.
Rinse the Cornish game hens briefly with cold water, then pat them completely dry with paper towels.**
Brush vegetable oil onto the birds, then rub seasoning salt on them. (Use about 1 teaspoon seasoning salt for each hen). Set aside for a moment.
Place the vegetables into 1 large or 2 small cast iron pans. Drizzle a little bit of oil on the vegetables, then sprinkle them with the remaining seasoning salt (about ½ teaspoon).
Set the hens on top of the vegetables.
Transfer the pan(s) to the oven. Roast, uncovered, until the thickest part of the game hens' thigh meat registers at least 165 degrees F. (about 1 hour). About 50 minutes into the roasting time, baste the chicken skin with the drippings that are in the pan.
Turn on the broiler and broil the hens for 3 to 5 minutes to really crisp up the skin. Watch very closely so the skin doesn't burn.
Recipe notes:
*You can substitute store-bought seasoning salt, if you prefer.**Make sure to get them really dry otherwise the skin will not get crispy.