Heat oil in a large skillet over medium heat until shimmering. Season chicken thigh pieces with salt and pepper, and place in skillet in a single layer. Add the shallots and cook until the chicken is lightly golden on both sides, about 7 minutes.

In a large pot, set 6 cups of water to the boil.

Meanwhile, combine the sugar, fish sauce, water, rice vinegar, hoisin, garlic, ginger, curry paste (if using) and peppers in a medium bowl. Whisk to combine, until sugar is dissolved.

When thighs are golden, add the sauce to the skillet. Bring to a good simmer and maintain to finish cooking the chicken, about 5 minutes. Sauce will thicken slightly. For a thicker sauce, sprinkle ¼ teaspoon of the corn starch over the top of the sauce with your fingers (to break up clumps). Stir well for one minute. If you want it thicker, add the remaining ¼ teaspoon.

Remove the uncooked rice noodles from the package and, without breaking, place in a large, deep sauce pan or wide stock pot sitting on a trivet or heat-proof surface. When the water boils, remove from heat and allow to settle for a few seconds, then carefully pour over the rice noodles. The noodles will begin to soften immediately and sink into the water. Start the timer. Check the noodles after 4 minutes by picking them up with tongs to test their texture. When cooked, they’ll be just short of al dente, like regular pasta, and not at all mushy. It’s far better to slightly undercook than overcook them, as rice noodles can get very mushy. Transfer noodles to a serving plate and set aside.

Taste the sauce, and adjust for salt and pepper as necessary. Stir in the cilantro. Serve over the rice noodles.