Without a fire, you will lack the ability to cook anything. You really need a fire to cook properly. Having a fire will make sure any cooking endeavors you attempt will not fail.
You cook your meal evenly by swinging (すい) it back and forth over the fire. You swing it left, you swing it right. You swing it to, you swing it fro. All this swinging ensures a properly cooked meal.
Currently there are no similar looking kanji which exist in the WaniKani learning system