Place the chicken in a large bowl and season with salt, pepper, lime juice, half of the minced garlic, and one tablespoon of Colombo powder. Marinate for 30 minutes.
Heat the vegetable oil in a heavy-bottomed pot or Dutch oven over medium-high heat.
Brown the chicken pieces in batches until golden on all sides, then remove from the pot and set aside.
Reduce heat to medium; add the chopped onion and remaining garlic to the pot, sautéing until translucent.
Add the remaining two tablespoons of Colombo powder to the onions and cook for 1 minute to toast the spices.
Return the chicken to the pot and add the cubed potatoes, eggplant, and thyme.
Pour in the chicken stock and place the whole habanero pepper on top, ensuring it does not burst.
Cover and simmer over low heat for 30 minutes.
Remove the lid, stir in the coconut milk, and continue to simmer uncovered for 15 minutes until the sauce thickens and vegetables are tender.
Remove the whole pepper and thyme sprig before serving over white rice.