I was finishing a jar of extremely hot peppers (7 pot primos) that I had fermenting on Thanksgiving day. I made a hot sauce with them and cantaloupe. I had them in a pan at a low simmer to meld the flavors. The problem was the steam coming off was potent as hell. It filled the house when everyone was arriving and coughing from the hot sauce in the air, me included. We had to open all the windows, dig out the fans to get it out of the house, freezing everyone in the process.
I was heating oil to deep fry some jalapeños. I put the cover on the pan so it would heat faster.
After a few minutes I took the cover off… and the oil instantly burst into flame.
I was fast enough to just drop the lid back on the pan, which killed the fire before it got worse… but yeah, don’t heat oil with a cover on. And have a fire extinguisher in your kitchen, one that’s properly rated for grease fires. Know how to use your fire extinguisher. Do not store it right next to the stove - you need to be able to reach it if there’s a fire.
You can also smother a grease fire by dumping baking soda on it. Do not dump flour on it, flour is flammable.
Flour isn’t just flammable; if it’s dispersed in the air like a cloud, like it probably would be if you hastily threw it into a grease fire, it can even explode.
Specifically, anything that is even slightly flammable (flour is starch, of course) can be violently explosive if it’s dispersed into air in the right (wrong?) way. That’s partly why water is such a terrible idea in grease fires.
Oxygen starvation seems like the safest bet. Like a huge, metal lid on a pot. I’d personally be skeptical of dumping anything into it at all, because of splashing.
From personal experience, salt also works. I keep a big box of salt with a big spout on my counter for more that just brining briskets.
Fire blankets are good, too.