Heat a large skillet over medium to medium-high heat and cook the bacon until chewy-crisp. Remove bacon to paper towel-lined plate to cool, and then roughly chop. Sprinkle beef with salt and pepper, and then sear beef in two separate batches, just until nicely browned on all sides. Transfer beef (leave excess fat in the skillet) and bacon to a large slow cooker on high heat. (If using a slow cooker like I own - the Cuisinart Cook Central Multi-Cooker - simply cook bacon and beef right in the cooker. Drain off fat once beef has cooked.) 

Stir in garlic, onion, chili powder, and cumin, and sauté until onion starts to soften, about 3 to 4 minutes. Add both cans of diced tomatoes (with the juice), beef broth, and soy sauce. Cover and cook for 4 hours on high heat. Stir in sweet potatoes, and then cover and cook for 2 hours more, or until sweet potatoes are tender.

Stir in corn, cover, and cook for 10 minutes. Stir in fresh lime juice right before serving. Offer lime wedges for squeezing over individual bowls of soup for even more bright lime flavor. Finish with a sprinkling of fresh cilantro.