Preheat oven to 400 degrees. In a bowl, whisk broth and cornstarch until dissolved. Whisk in mustard, silan, honey, lemon juice, salt, pepper and chile flakes. Season chicken generously with salt.
Preheat the oven to 200C/180C Fan/Gas 6 ... of pink when the thickest part is pierced with a skewer. Take the chicken thighs out of the roasting dish, leaving the marinade behind.