Heat a large skillet over medium heat. Coat the pan with olive oil, and when the oil is hot, sauté the garlic until it slightly browned.
Add the onion, and add more oil if needed. Cook the onions until they are translucent.
Add the turmeric, cumin, coriander, and onion powder, and mix to coat the onions and garlic.
Then add the sweet potato and celery. Add water and salt.
Let everything simmer until the sweet potatoes are soft and cooked through.
Add the cooked chicken and coconut milk, and continue simmering to mix the flavors.
Serve over cooked brown rice and top with the sliced avocado.