Preheat your oven to 375°F (190°C).
In a large skillet, cook the ground turkey or beef over medium heat until browned. Drain excess fat if necessary.
Add the diced onion and minced garlic to the skillet. Cook for about 5 minutes until the onion is soft.
Stir in the frozen mixed vegetables, dairy-free cream of mushroom soup, vegetable broth, dried thyme, salt, and black pepper. Mix well until combined and heated through.
Pour the meat mixture into a 9x13 inch baking dish, spreading it evenly.
Top the mixture with frozen tater tots, arranging them in an even layer.
(Optional) Sprinkle dairy-free cheese over the top of the tater tots.
Bake in the preheated oven for 30-35 minutes, or until the tater tots are golden brown and crispy.
Let the casserole cool for a few minutes before serving.