In a bowl, stir together the turmeric, coriander, garlic, fish sauce, erythritol, lime juice, olive oil, 1/4 tsp salt, and a few grinds of pepper.
Place the marinade and chicken in a ziplock plastic bag and refrigerate for at least 30 minutes and up to 4 hours to let the flavors combine. Meanwhile, soak 4 (6 to 8-inch) wooden skewers in water.
Preheat the broiler. Line a rimmed baking sheet with aluminum foil.
Thread the marinated chicken and vegetables onto the soaked skewers, dividing everything evenly among them and packing all items tightly. Alternate between chicken and vegetables on each skewer.
Place the kebabs on the prepared baking sheet in one layer. Broil the kebabs about 6 inches from the heat, turning occasionally to caramelize all sides, until the chicken is cooked through, 15 to 20 minutes, depending on heat and size of the chicken pieces. Plate 2 kebabs each on 2 dinner plates. Season to taste with salt. Drizzle each with half of the melted butter, and serve.