The device you want to use, IF no thermostatic control is desired, is a burst control dimmer rated for the power. A phase angle dimmer at that wattage will be an EMC liability, a resistor will be very energy inefficient, huge and a fire risk, and a variac is bulky and expensive.
Note that common household light dimmers are a) phase angle designs and b) too weak.
However, using some kind of thermostat that switches in the heating if more heat is needed and switches it off when it is getting too hot might be the more desirable solution.
For a VERY simple power dropper (also inefficient, but safer than a resistor) put very high powered incandescent lights (maybe a few of them paralleled), like construction lights, in series with the heating element. Set them up so they operate safely, these lights get hot too!
Some kind of overtemperature cutoff device in the smoker would be very well advised unless the whole smoker design is inherently, absolutely impossible to set on fire, even if the element was running at full power - which is a possible failure mode in case your method of heat control fails - and it will if you expect it not to.
If you have any doubt about your design being safe, consult a professional electrician.