Heat oil in a large skillet over medium-high heat.
Add the onion and saute until they begin to soften.
Add garlic and jalapeno (if using) and saute another 1-2 minutes, until fragrant.
Add beef, bell pepper, tomato paste, and spices. Break up the beef with a spatula or spoon, and saute until the beef is browned.
Once beef is browned and cooked through, turn heat down to low and cook for another 5-10 minutes, stirring occasionally. I usually don’t have to add extra liquid, but you can add a bit of water or stock if you findthe mixture to be too dry.
Meanwhile, heat up the tortillas. If you have a gas stove, turn the flame on high and use metal (heatproof) tongs to place the tortilla directly on the flame. Heat for about 5-10 seconds, then flip with the tongs and heat the other side for 5-10 seconds. Remove with tongs and turn off flame.
If you don’t have a gas stove, you can heat in the microwave. Place 4-5 tortillas on a plate, cover with a damp (not soggy) paper towel, and microwave in 30 second intervals until heated through.
Stuff corn tortillas with beef, optional toppings, and goji hot sauce!