In a large skillet, heat olive oil over medium-high heat. Once the oil is hot, add diced onion and cook until they begin to soften, approximately 3 minutes.
Add beef and cook until browned, approximately 4-5 minutes.
Remove from heat and add to the bowl of a slow cooker.
Add the remaining ingredients for the chili to the slow cooker. Stir to combine.
Cook on high for 4 hours.
Serve immediately with sliced avocado, sour cream, shredded cheese, cilantro, tortilla chips and extra sliced jalapeƱos for added heat!