Preheat oven to 220°C | 430°F. Spray a baking tray/sheet with nonstick spray and arrange sweet potatoes the tray. Roast for one hour in the oven, or until soft (check them after 40 minutes, pierce with a fork, and continue roasting if needed).
While the sweet potatoes are cooking, add a small amount of oil to the pan; add the onions to a skillet/frying pan over medium-high heat. Once transparent (about 1-2 minutes), add the chicken, garlic and capsicum/peppers. Cook until the garlic is fragrant. Add in the seasonings and continue cooking until chicken is completely coated in the seasonings. Mix the beans through; take off heat and set aside
Remove the sweet potatoes from the oven; allow them to cool for about 5 minutes until they are just warm enough to handle (not until they're completely cold); and carefully slice them in half. Slice around the inside of the skin, leaving 1cm 'wall' around the inside of the skin. Slice small cubes into the flesh for easier removal. Scoop out the flesh and transfer it into a medium-sized mixing bowl. Set the skins aside.
Add the chicken fajita mixture to the flesh in the bowl; mix it through until completely combined. Stir in the lime juice.
Arrange the skins on the same baking tray/sheet, and stuff them with the fajita sweet potato mixture. Sprinkle with cheese and the coriander/cilantro leaves. Put them back into the oven for 15-20 minutes until cheese is bubbling and starting to brown (or place under the grill/broiler in the oven for golden, crispy cheese for 10 minutes).
Serve with any left over coriander/cilantro leaves, lime wedges, avocado pieces and smother in salsa dip.