Chop the leftover veggies and sauté on the griddle. Cook on medium for 2-3 minutes.
While the veggies are cooking, crack the eggs into a medium-sized bowl, add half & half, and whisk. Add the remaining ingredients, including sautéed veggies and chopped steak, to the same bowl and mix.
Reduce the griddle heat to low and place the omelet ring with olive oil in the center.
Pour the mixed ingredients into the ring. Cover with the dome and add water inside to steam.
Cook for 15-25 minutes, depending on the frittata's size. Once the top is solidified, the frittata should be cooked through. Use a toothpick to check the middle; if it comes out almost clean, it's done. Add steam under the dome every 5 minutes. Check the bottom of the frittata to avoid burning.
Turn off the griddle.
Move the frittata with the ring onto a cutting board to cool (approximately 10 minutes).
Use a knife to gently release the frittata from the ring. Shimmy the ring as you lift to prevent breakage.
