Steaming with oil instead of water

That really wouldn't work.

With steaming the water is heated to boiling which creates steam. Since the food is colder, the steam condenses on the food which transfers heat to the food.

With hot oil there is no boiling and vapor of the oil. So in an enclosed container it would be more akin to baking, the hot oil heating the air, than steaming. (There would be some oil in the vapor above hot oil, but not enough to transfer much heat.)

(1) Another factor here is pointed out by user "Lorel C" in another answer. Cooking oils tend to decompose and smoke before reaching their boiling point. If you could get oil to boil without smoking, then "steaming" in the boiling oil vapor would be very close to frying in oil, but at a temperature much above what is normally used.

(2) Also as user "yo" points out in a comment below, the bubbling that you see when frying something isn't the oil boiling. Rather it is the water coming from the food that is vaporizing.

I have never heard of anyone "steaming" vegetables using oil instead of water. Placing them in a metal frame above hot oil would not be as effective as cooking them surrounded by steam (from water). The hot oil would need to be boiling.

According to
https://www.researchgate.net/post/What_is_the_boiling_temperature_of_cooking_oil_palm_oil_Any_reference

Q & A on cooking oil,

"The exact boiling temperature depends on how pure the oil is. The boiling point for palm cooking oil is estimated in about 300 C (or 572 F)." That kind of temperature seems like overkill for vegetables. Also the smoke point for cooking oils is lower than their boiling point, so it would be messy, unpleasant (with all that smoke in the kitchen), and, judging from the comments contributed by others, it would be extremely, crazy-dangerous as well.

As already said, this wouldn't work at all with any normal fat. I'd further emphasize that it's really quite dangerous: fat can spontaneously ignite when heated substantially over the smoke point. And if you drop anything water-containing (like one of the pieces of vegetable) into hot fat, the water will boil with a sudden violent expansion. When the fat is already aflame, this can result in a literal fiery explosion. (The reason why fat fires must never be extinguished with water.)

That said, if you use a pure, saturated, short-chain fatty acid like lauric acid, you could get this to work because it chemically withstands the 300°C needed to get it boiling. These vapours would then indeed “steam” your vegetables. It would not actually get the vegatables to 300°C because the water content has a high heat capacity; a lot of fatty vapour would need to condense on the surface to even reach 100°C. I reckon the result would actually be more like soaking the vegs in a cold deep-fryer, which is then heated up slowly. If you'd do it long enough, the water would eventually evaporate, after which the temperatures would go up much higher – the food would eventually be dry-singed.

Pure lauric acid isn't toxic, but it would probably impose a soapy/waxy taste on the food.

You can, but the oil will smoke before it boils and the oil will require a lot of heat to actually come to a boil.

It's possible, but really really inefficient.

https://www.oliveoilsource.com/asktheexpert/what-boiling-point-olive-oil

According to that article it would also be dangerous.

Most importantly, from an objective standpoint, you would heat the oil up too much and ruin the flavor. Your vegetables would not taste good if you did this.

I'm assuming that you're just looking for cool ways to cook stuff at this point. You should try roasting things with sand or salt. The youtube channel cookingshooking has a lot of videos where the host cooks things like pizza without an oven using salt in a pressure cooker. This would cook your vegtables well in a unique way.

If you want your vegtables to be coated in a little bit of oil then you can just sprinkle oil on them or toss them in a bowl with oil to coat them.

Even if you could steam oil without it combusting, it wouldn't transfer nearly as much energy as steam does.

Water has an obscenely high specific heat, just around 4. Here

Oil has a specific heat around 2, depending on the type of oil. Here, Table 6

it takes approximately one crapload of energy to turn water into steam. That energy is still in the steam as it rises, and is transferred to anything that it touches. That is why steam has a such a high scald hazard despite being 'only' 100 C. Oil, with its lower specific heat, would not transfer energy as efficiently.

Yes, you can "steam" using oil. When you steam with water, the hot water condenses on the cold food and transfers the heat. With oil, you mist the food with oil and then heat the air. The oil transfers the heat to the food. It's called "air frying."

https://www.buzzfeed.com/michelleno/philips-airfryer-review

You can in fact. It would not be practical and traditional streaming methods are more precise and less dangerous however, when frying particularly moist foods (like fries) especially in large quantities, steam is produced. This steam isn't enhanced with flavor and there really isn't any benefit to doing it this way. Which is probably why it isn't.

Possible to do this safely in an atmosphere without Oxygen, but it would still taste bad.

As other answers mention, the smoke point is lower than the boiling point, so food cooked in oil vapor would taste horrible. By removing the Oxygen, you won't prevent smoking. But you will reduce the fire hazard.

One method to do this, and prevent other reactions between the hot oil and the air, would be to remove all the normal air from a room and replace it with a much less reactive Helium.

For obvious reasons, this is not a frequently used cooking method. When someone does this, it will make a great youtube video. Perhaps the food will taste good too.