Preheat oven to 325℉.
Preheat Dutch oven on stovetop on medium-high heat. While pan is preheating mix all dry rub ingredients together and rub all over brisket.
Add avocado oil to hot Dutch oven and sear brisket on all sides for 2 minutes per side.
Remove brisket from Dutch oven and place on baking sheet. Add onions, sauté until lightly browned, about 2 minutes.
Add tomato paste and stir for 30 seconds. Add mustard, stir to combine with onions and tomato paste.
Deglaze with vinegar, scraping the bottom of the Dutch oven to loosen the browned bits.
Add apricots and apricot nectar, stir. Return brisket and any juices on baking sheet to Dutch oven. Place lid on and put in preheated oven for 4 hours.
Let brisket rest in braising liquid for 30 minutes before slicing against the grain.
Serve with braising liquid as a sauce and enjoy!