In a saucepan, heat the oil and cook onion, red bell pepper and garlic for 2-3 minutes.
Add tomatoes, black beans, green chili, sugar, chipotle chile powder, cumin and chicken.
Bring to a boil over medium-high heat.
Place tortilla chips on baking sheet or stone.
Using a slotted spoon, top tortilla chips with chicken chili fixings.
Spread cheddar over the top of everything.
Broil until cheese is melted and chips are beginning to brown. Watch it close so you don't burn it!
Stir sour cream and chipotle chile pepper together. Dollop on top of finished nachos.