In a medium sized bowl marinate the shrimp with turmeric, black pepper, salt, garlic powder, vinegar and olive oil. Rest in the fridge for 30 min to 1 hour.
In a large saucepan, heat the vegetable oil. Add the finely minced ginger, garlic and onion, sweat until the ingredients are soft and have reduced, about 3-4 minutes. Then, add the Jamaican curry powder and cook for 1-2 minutes to activate the spices. Incorporate the diced potatoes and sauteé until the edges become translucent. Add the scotch bonnet, thyme sprigs, chicken stock and coconut milk, once the liquid begins to boil, allow to simmer for 10 minutes.
Mix the cornstarch with a couple of tablespoons of cold water and incorporate it into the sauce along with the salt. Cook until the sauce boils and thickens, then add the shrimp and poach in the sauce until they are cooked and have a nice pink color (about 4-5 minutes on medium heat).
Serve Jamaican Shrimp Curry with a side of rice and fried sweet plantains.