For the beef filling:

1. Heat oil in medium skillet over medium heat until hot and shimmering but not smoking, about 2 minutes; add onion and cook, stirring occasionally, until softened, about 4 minutes. Add garlic, spices, and 1/2 teaspoon salt; cook, stirring constantly, until fragrant, about 1 minute. Add ground beef and cook, breaking meat up with wooden spoon and scraping pan bottom to prevent scorching, until beef is no longer pink, about 5 minutes. Add tomato sauce, chicken broth, brown sugar, and vinegar; bring to simmer. Reduce heat to medium-low and simmer, uncovered, stirring frequently and breaking meat up so that no chunks remain, until liquid has reduced and thickened (mixture should not be completely dry), about 10 to 20 minutes. Adjust seasonings with salt and pepper. I added hot sauce to my mixture, but you don’t have to. Make sure you taste it before you serve it up!

For the taco shells (see photos below):

1. In a small shallow pan, heat about 1 to 2 inches of canola oil to 350 degrees. Hold one end of each tortilla with tongs, and hold down the other end with a heat-proof spatula in the oil until it sets up, about 10 to 15 seconds. Switch positions and fry the other side until you get a somewhat perfect shell, then repeat on the other side again until it’s evenly crisp. They won’t be 100% perfect, but they’ll be delicious! If you don’t have a thermometer to test the temperature of your oil, just tear off a piece of a tortilla and put it in the hot oil — if it floats after a few seconds (about 5) it’s ready. If it doesn’t float at all, it’s not hot enough — and if it burns immediately, its too hot!
2. Drain each shell on paper towels and season with salt while they’re still very hot.