Heat the oil in a 12-inch skillet over medium heat until shimmering; add in onion and cook, stirring occasionally, until softened, about 5 minutes.
Add in the chili powder, garlic,, cumin, coriander, oregano, cayenne, and 1/2 teaspoon salt; cook, stirring constantly, until fragrant, about 1 minute.
Add in the ground beef and cook, breaking the meat up with a wooden spoon, until the beef is no longer pink, about 5 minutes.
Add the tomato sauce, chicken broth, vinegar, and brown sugar and bring to a simmer.
Decrease heat to medium-low and simmer, uncovered, stirring frequently and breaking the meat up so no chunks remain, until the liquid has reduced and thickened (mixture should not be completely dry), about 10 minutes.
Season with salt and pepper to taste.
Divide the filling evenly among the warm taco shells and serve.