Preheat Grill or Smoker to 375 degrees F using cherry wood.
In a 12-inch large cast iron pan over medium heat add olive oil. Add ground beef or lamb, dust with dry rub, and stir to brown (about 8 minutes). Remove beef and side aside. (If the fat from the beef has cooked off, you may need to add 1/2 tablespoon of olive oil prior to adding the vegetables. Otherwise leave the liquids that remain from the meat).
In the same cast iron pan, over medium heat, add onions and carrots and sauté about 5-7 minutes until starting to soften. Add garlic and cook 1 more minute.
Add the meat back to the vegetable mixture. Then add the flour and combine until dissolved.
Add the wine, broth, tomato paste, Worcestershire sauce and simmer 2-3 minutes.
Mix in the herbs, peas, corn, and seasonings and toss together. Cook about 5 minutes to let everything integrate.
Gently coat the mashed potatoes evenly over the filling. Add peaks and valley's using a fork to make S-patterns along the potatoes.
Place the cast iron skillet with the Shepherd's Pie in the grill, over indirect heat, for 35-40 minutes, until the potatoes are lightly browned and the filling is bubbly. Serve and enjoy!