There are a lot of attractive, hard-wearing, great quality frying pans available for decent prices these days. The avid home cook probably has two or three dedicated frying pans in their arsenal because you can cook a great many ways in the humble skillet—fry, sauté, steam, or braise. Unfortunately, many frying pans don’t come with lids. Instead of scouring the internet for the right fit, just use an overturned mixing bowl.
Exactly zero of my frying pans came with a lid. I don’t think about it a lot when I’m purchasing a pan, but I often need to improvise a lid. Usually it’s for a grilled cheese, or panini-style sandwich I’m trying to heat through. Frying pans are designed to let steam escape and encourage air flow, so the bottom is the only point of heating. That’s great for searing, and toasting the exterior bread of my cubano, but the cheese in the center will never heat through before the bread burns. That’s where the lid comes in.
Putting a lid, or an upside-down bowl in this case, on the pan traps steam and allows the heat to build around the food in the pan so you can melt that cheese in the center. The same method is used for flash-steaming frozen gyoza to help heat the filling in the center. After a few minutes, you take the lid off, let the steam go, and crisp up the bottom.
By now you might have two or three frying pans you reach for on a regular basis, and they’re all different sizes. The reason mixing bowls function well as lids, especially a nesting set, is because most circular items in your kitchen (bowls, pans, pots, cake pans) reflect each other in diameter. Usually by inch integers—six, eight, 10, 11, and 12 are the most common. If you have a set of four or six mixing bowls, the odds are pretty good you’ve got a bowl that matches up with your frying pan.
Using a metal mixing bowl as a lid is easy. Grab a bowl, flip it upside-down and carefully place it over the pan so the lip of the bowl rests on the top edge of the pan. The shape of the bowl keeps it clear of the pan’s angled handle, as opposed to an oversized plate that would bump into it. If the lid slides off to one side, you probably need to use a size down. If the lid falls into the pan, then you need one size up. If you don’t have a good match then you could technically use the too-small bowl as a “tight fitting” lid, or the too-big bowl as a loose lid (steam will escape out the open edge).
Make sure you’re using a metal mixing bowl, not glass. Besides being a heck of a lot lighter, regular glass bowls and even heat-resistant glasses can break due to thermal shock, and that is a harrowing experience (I wish it upon mostly no one).
Be careful taking the metal bowl off the pan. Not only is the bowl in direct contact with the pan’s 300+°F hot edge, but the bowl’s dome will be filled with 212°F steam. Use oven mitts to protect your fingers and use two hands to take the hot bowl off.
There are quitters out there who'll go buy a set of lids, but why unnecessarily dig into your budget and take up extra space in your kitchen cupboard? Personally, I think the versatility alone is worth it. I'll ask this: Can you mix cookie dough or marinate steaks in a regular, flat pan lid? I rest my case.