Diagnosis
Grease and food spatter from cooking accumulate on the exposed heating coil at the top of the chamber. This can smoke.
How to Fix It
Unplug and let the unit cool completely. Remove basket. Use a soft-bristle brush (a dry toothbrush works) to gently dislodge loose debris. For stuck-on grease, dampen a cloth with warm water and mild soap. Wring it out completely. Wipe the coil gently. Follow with a dry cloth. Never submerge or run water into the top.
If That Didn't Work
For stubborn carbon, use a dedicated ceramic cooktop cleaner on a cloth. It's less abrasive. Apply to the coil, let sit, then wipe. Avoid the surrounding housing.
Heads Up
Never use metal scouring pads or abrasive powders. You can nick the coil coating or bend the element. Do not clean while the element is even slightly warm.