Peel your sweet potatoes thoroughly with a vegetable peeler. Cut them into equal-sized cubes. Small chunks cook faster and more evenly. Rinse them under cold water to remove excess starch. This helps the texture stay smooth.

Place the cubes in a large pot of salted water. Bring the water to a boil over high heat. Reduce to a simmer and cook for 15-20 minutes. Test them with a fork. They should be very soft when pierced.

Pour the potatoes into a colander to drain. Return them to the hot pot for one minute. Shake the pot over low heat. This evaporates any remaining water. Dry potatoes absorb butter and cream much better.

Use a potato masher or a ricer for the smoothest finish. Mash the potatoes while they are still very hot. Do not let them cool down. Cold potatoes become gluey and sticky. Keep mashing until no lumps remain.

In a small pan, heat the heavy cream and butter. Add the vanilla seeds and chili flakes. Let it simmer gently for two minutes. This allows the flavors to blend. Warm liquid mixes into the mash more easily.

Slowly pour the warm cream mixture into the mashed potatoes. Stir gently with a wooden spoon. The potatoes will soak up the liquid quickly. Keep stirring until the mixture looks silky and glossy.

Add the lime juice and lime zest now. Season with a generous pinch of salt and pepper. The lime adds a fresh zing that cuts the sweetness. Taste a small spoonful. Adjust the salt if you need more flavor.

Transfer the mash to a warm serving bowl. Sprinkle fresh chopped chives over the top. You can add an extra knob of butter if you like. Serve it immediately while it is hot and fragrant.