Preheat the oven to 400oF (204oC) and line a baking sheet with parchment paper.
In a medium-sized bowl, add the lamb, thyme, garlic and half the sea salt. Mix well with your hands to combine everything. Roll the mixture into golf ball-sized balls and set aside.
Add the brussels sprouts and cauliflower to the pan along with the avocado oil and sea salt. Toss to combine. Place the meatballs on the pan in between the veggies. Bake for 30 minutes. Remove, serve and e