How to Make It
Season the chicken inside and out with the 2 1/2 teaspoons of salt, then tie the legs together with kitchen string, if desired. Refrigerate uncovered for at least 5 hours or overnight. Let the chicken come to room temperature before roasting.
Preheat the oven to 500°. Put the chicken in a small roasting pan or large skillet. Roast for 30 minutes, until lightly browned. In a small bowl, whisk the mustard with the soy sauce, then spoon the glaze all over the chicken. Roast for 20 to 30 minutes longer, until an instant-read thermometer inserted in the inner thigh registers 162°. Transfer to a carving board and let rest for 10 minutes.
Meanwhile, in a small bowl, mix the carrot greens with the vinegar, oregano, lime zest, garlic and crushed red pepper. Gradually whisk in the olive oil until combined. Season the chimichurri with salt.
Carve the chicken. Thickly slice the breast against the grain. Transfer the chicken to a platter and serve with the carrot top chimichurri.