Heat a large Dutch oven or heavy-bottomed pot over medium heat. Add the coconut oil and swirl to melt and coat the base of the pot. Add the onion, ginger, garlic, cilantro stems and 1/2 teaspoon salt. Cook, stirring occasionally, until the vegetables are softened, about 5 minutes.
Add the tomato paste and stir to coat the vegetables. Add the curry powder, cumin, coriander and cayenne and stir to combine and toast the spices. Add the tomatoes, stock, and potatoes to the pot. Bring the mixture up to a boil, then turn the heat down to low, cover the pot and let simmer until the potatoes are very tender, about 25 minutes.
Add the turkey and peas to the pot and simmer until heated through, another 5 minutes. Turn off the heat and stir in the cream and lime juice.
Ladle the curry into bowls and garnish with the chopped cilantro. Serve with rice, if desired.