After 50 minutes of braising, the ribs should be cooked through and tender. But the actual cooking time depends on the age of the animal and the quality of the meat. If the ribs aren't done and there's too little liquid in the pan, pour in more bone broth, a quarter cup at a time, and continue simmering until the meat is tender.
Rinse the rack of ribs then pat dry with a kitchen towel. Cut between the bones.
In a heavy and wide non-stick pan, arrange the ribs in a single layer, fatty side down. Sear until the fat starts to melt and the underside is nicely browned. Give the ribs quarter turns to sear all sides.
Pour in the broth. Sprinkle in the rosemary, thyme, sage, onion flakes, chilies, salt and pepper. How much salt and pepper you need to add depends on how well-seasoned your bone broth is.
Bring to the boil, lower the heat, cover and braise for half an hour.
Turn the ribs over and braise for another 20 minutes.
Scoop out the ribs and move to a plate.
Stir together the mustard, honey and balsamic vinegar. Pour into the pan. Swirl to blend. Boil, uncovered, for four to five minutes until thick. Turn the heat to low.
Put the ribs back on the pan. Simmer for a minute. Flip them over and simmer for another 30 seconds.
Notes
You may use fresh sweet yellow onion in lieu of dried onion flakes but I find that the concentrated flavor of dried onion works so well in braised dishes.