Place the goat pieces into a large mixing bowl and rinse quickly under cold water; if using vinegar or lemon juice, splash it over the goat, rub lightly with your hands, then rinse again and drain well.​​

Add 1½ tbsp curry powder, salt, black pepper, ginger–garlic paste, chopped onion, and thyme to the bowl and mix thoroughly with a wooden spoon so every piece is coated.​

Cover the bowl with plastic wrap and set it in the fridge for 120 minutes so the goat absorbs the curry and aromatics.​

Set a large heavy pot or Dutch oven on the stove over medium heat and pour in the vegetable oil with a measuring spoon.

When the oil looks hot and shimmery, sprinkle in 1½ tbsp curry powder and stir constantly with a wooden spoon for 30 seconds to 1 minute until the curry smells toasty and the oil turns bright yellow.​

Add the seasoned goat pieces from the bowl into the pot in a single layer as much as possible and cook for 10 minutes, stirring every few minutes with the spoon, until the outside of the meat is lightly browned.​

Add the sliced onion and chopped scallions to the pot and cook, stirring with the wooden spoon, for 5 minutes until they soften.​

Stir in the minced garlic and grated ginger and cook for 1 minute, stirring often so the garlic does not burn.​

Add the tomato paste and cook for 2 minutes, stirring with the spoon to coat the meat and onions until the paste darkens slightly and smells richer.​

Drop the whole or pierced Scotch bonnet pepper into the pot and stir it gently into the curry base with the spoon.​

Pour 4 cups water or broth into the pot using a measuring cup, stirring with the wooden spoon to mix and scraping the bottom to release any browned bits into the liquid.​

Add salt and allspice if using, then bring the pot up to a gentle boil over medium-high heat.​

Once boiling, turn the heat down to low, cover the pot with its lid, and simmer for 90 minutes, stirring every 20 minutes with the spoon so nothing sticks and the goat cooks evenly.​

After 90 minutes, check a piece of goat by lifting it out with a spoon and pressing it with a fork on the cutting board; it should feel mostly tender but can still have a slight bite.​

Stir the potato chunks into the pot with the wooden spoon, making sure they sit under the liquid, and continue simmering covered on low heat for 30 minutes until the potatoes are soft and the stew has thickened.​

Remove the Scotch bonnet pepper with a spoon, then taste the stew and adjust salt if needed using a measuring spoon; if the sauce feels too thick, add a small splash of hot water and simmer a few minutes, stirring with the spoon.