The Paella Pan made of

The way to make a proper griddled hamburger:

Start with beef that is between 70/30 and 80/20. You need to use a fatty beef because you are going to be doing a few things that will restrict the amount of juice in the burger and the extra fat will mitigate that.

Season your beef and roll into balls less than 1/4 of a pound. Let the size of your patties be determined by the size of your pan, you need them small enough that once you smash you won't be touching the sides of the pan.

You then want to preheat your pan. You want your pan to be as hot as possible. A commercial griddle can range in heat between 375 F and 650 F, so the temp here can vary quite a bit between places, I find hotter aids crust formation and allows the interior stay closer to medium.

Do not use oil. I can't stress that enough. Your beef will put out plenty and oil will fry the burger instead of allowing a seared crust to develop.

Place your balls of meat on the pan and smash them flat with a spatula. You might need a second spatula to remove the patty from the smashing one, as you lack the space space to heat it like you would on a griddle to prevent sticking. Allow it to cook about two to three minutes, then flip and top with cheese, if desired. Two more minutes and remove.

As an added bonus, you can toast/fry some bread in the beef juices to create a patty melt style burger that will be oozing beefy goodness. You can drop the bread in right after the flip and it will be perfect by the time the patty is done.

I don't want to disappoint you, but I have never been able to remove burnt-on pepepr juices - and in my case, they are on stainless steel, which can be cleaned with much harsher methods than non-stick. Most of the stuff went away, but small spots remained on my pot too.

I would advise to leave out all scrubbing. It is not very efficient even on steel, and it can easily damage a non-stick surface. Non-stick happens to be a chemically inert molecule, but it is very susceptible to physical damage.

The nice side of "chemically inert molecule" is that it can withstand a lot of chemical solvents - and these are better for burnt-on stuff anyway. I would go in there with concentrated acid first (citric acid solution at around 2 pH - try it in the same way as decalcifying a kettle, but use a higher concentration than written on the sachet), then, after a really good washing, switch to a base (for example a very concentrated baking soda solution, I would be afraid to use lye on a non-stick pan because it could seep through scratches to the interface between alu and non-stick surface and start corrosion spots). If that doesn't help, probably nothing will.

And I would strongly recommend to not roast peppers in a non-stick pot. Roasted peppers need very high temperatures. Non-stick coatings start changing their properties at around 250°C, this is a low-to-middle hot setting on most stoves (my resistive stove goes from 1 to 9 and 4 is already too hot for non-stick). The best method is a broiler in the oven, but if you don't have that, you can consider using a steel or iron pan which you don't mind accumulating some discoloration and spots (they are not too problematic on steel), or putting alu foil directly on the (resistive) hob and discarding it after the roasting.