Dice the onion finely and mince the garlic and ginger. Set these aside.
Heat the vegetable oil in a large pan over medium heat. Add the diced onion and sauté until soft and translucent, about 5 minutes.
Add the minced garlic and ginger, cooking for an additional 2 minutes until fragrant. Stir in the curry powder and turmeric, and cook for 1 minute to release the spices' aromas.
Cut the chicken breast into bite-sized pieces and add to the pan. Cook, stirring frequently, until the chicken is browned on all sides, about 5 minutes.
Pour in the chopped tomatoes and coconut milk. Stir well, bring the mixture to a gentle simmer, and cook for 15 minutes until the chicken is cooked through and the sauce has thickened.
Season the curry with salt and black pepper to taste. Stir in the freshly chopped coriander. Serve hot with a wedge of lime on the side for squeezing over before eating.