Heat oil in a skillet set over medium heat. Add the onion, garlic, thyme, rosemary, and half of the salt and pepper. Cook, stirring often, for 5 to 7 minutes. Preheat the oven to 350 F (180 C).
Crumble meat into pan and cook until brown all over. Sprinkle with flour. Stir in ketchup, tomato juice, Worcestershire sauce and mustard. Simmer for 5 minutes. Stir in mixed vegetables. Transfer to a 9-inch (23-cm) baking dish.
Whip the potatoes with the warm milk, remaining salt and pepper, butter and garlic until very fluffy. Spread potatoes evenly over meat mixture. Bake for 35 minutes or until potatoes are golden.