Heat the olive oil in a large skillet over medium heat. Add the diced onion and sauté until translucent, about 5 minutes.
Stir in the minced garlic and grated ginger, cooking for an additional minute until fragrant.
Add the chicken pieces to the skillet, cooking until browned on all sides, about 5-7 minutes.
Sprinkle in the turmeric, cumin, coriander, and cayenne pepper, stirring to coat the chicken evenly with the spices.
Pour in the coconut milk, stirring to combine. Bring the mixture to a simmer, then reduce the heat to low.
Add the diced zucchini and mango, stirring gently. Cover and let simmer for 15-20 minutes, or until the chicken is cooked through and the zucchini is tender.
Season with salt and pepper to taste.
Serve the curry over cooked rice or quinoa, garnished with fresh cilantro if desired.