Dice the sweet potato into small cubes and finely chop the red onion and bell pepper.
Heat olive oil in a large pot over medium heat and sauté the onion and pepper until softened.
Crumble the tempeh into the pot and cook until slightly browned, then stir in the sweet potato cubes.
Add the chili powder, cumin, smoked paprika, garlic powder, salt, and pepper, stirring to coat the vegetables.
Pour in the diced tomatoes, black beans, vegetable broth, and maple syrup, bringing the mixture to a gentle boil.
Reduce heat to low, cover, and simmer for 20 minutes until the sweet potatoes are fork-tender and the flavors meld.
Serve the hot chili in a large bowl and top with the Greek yogurt for a velvety finish.