Preheat the oven to 400ºF.
Trim any excess skin or fat from the chicken thighs, and then put them in a large bowl.
Sprinkle with the teaspoon of salt, then toss with the mustard until evenly coated.
Put the panko, thyme and salt and pepper in a pie plate, and stir to combine.
Press the chicken into the panko mix on both sides, shake off any excess, and transfer to a rack over a rimmed baking sheet.
Put the pan of chicken in the oven and cook for until the chicken has an internal temperature of at least 175°F, and the panko crumb crust is golden brown, about 1 hour.
Transfer to a serving platter, let the chicken cool for 5 minutes, then serve.
