I typically finish my projects in 4 ways; wax, polyurethane, shellac or clear epoxy. Occasionally, I'll finish with an oil.
Wax: A wax finish is usually done first on the lathe where I'll spin butcher's or bees wax into the project. I then wipe it down with Howard's Feed & Wax, a mixture of wax & orange oil.
Polyurethane: Finishing anything with polyurethane requires a minimum of 3 coats, sanding between each. I use only gloss polyurethane for the base coats as the satin finishes are created by microscopic bubbles which makes a weaker finish. My satin polyurethane finishes are done with a final spray coat of satin over top of the final, sanded gloss coat. I generally apply the polyurethane with a Viva paper towel to get a thin, even coat.
I also use water or latex based polyurethane on light colored woods where even shellac will show its color. I'm not particularly fond of it as it raises the grain & is harder to make into a smooth finish. It looks horrible on darker woods, leeching their color rather than enhancing it. On a white wood like Holly, it doesn't color the wood, except to make it a bit lighter.
Shellac: Quick drying, I generally use it when I want a simple, thin finish or to seal the wood. Its alcohol base lets it seal resin into pines that would bleed through polyurethane. I often cover it with another finish. It is hard to build any depth with shellac by itself. A second coat tends to dissolve the first & orange shellac makes a streaky mess. To build up a good finish takes a couple of hours with a thinned mixture of shellac & a dash of linseed oil. A pad is used to rub on a few drops at a time until it is completely dry. After 30 minutes or so, it usually starts to get tacky, so you have to stop for a day or two before doing another round. This is also known as a 'French Polish'. It's my favorite look, but few want to pay for the time it takes & it isn't as durable as polyurethane.
Clear coat epoxy: This gives a lot of depth & gloss - more than I'd like sometimes. It also penetrates more than any other finish & has a lot more strength. I usually use it on natural edge bowls where the bark would fall off without it. It is also perfect for filling voids in the bottoms of bowls. Its main drawback is that it is very expensive & time consuming to apply. It only works well in a narrow temperature range & is very prone to bubbles. I tend to use US Composites Kleer Koat since it is the only epoxy I have found that is truly clear. It's a drag to work with compared to most of the other epoxies out there. It is much thicker since it was designed to make a thick clear coat, often to seal items into table & bar tops. I use West Systems epoxy when I don't need super clear epoxy. It has a brownish tinge, much like oil based polyurethane.
Oil: Tung & Linseed oils are the two I'll use most often. Both take a long time to dry & can't be used if there is bark in the bowl, so I don't use them often. I also use Mineral or Walnut oils to finish a bowl that can be used for food.
Bowls & Food Safety
I don't guarantee any bowls as food safe, although that doesn't mean I wouldn't eat out of any of them. Food safety is complex & very dependent on a lot of factors from the type & quality of the wood to the type of finish & its care. Most of my bowls are decorative & often contain rough areas & voids. They should never be used for any sort of food.
Most 'food safe' wooden bowls are made out of 'tasteless' woods such as maple, beech, sycamore, birch or poplar. The wood itself will not flavor the food & were often used by colonial settlers for this purpose. They didn't realize that the pores in wood could act as a breeding ground for bacteria, although they did finish most of their bowls with some type of oil that acted as a barrier between the food & the wood. They also tended to use wooden implements that didn't scratch through this barrier - less common today in the age of hard plastics & inexpensive metal implements.
Hard finishes, such as polyurethane, are not good for salad bowls since they can deteriorate & chip. While clear shellac or polyurethane is supposed to be non-toxic, a chunk of the finish in a salad would spoil it for me & any defect in the finish creates a breeding ground for bacteria.
Historically, many different kinds of oils have been used. Today, Walnut oil is used to flavor many salads & can protect the inside of the bowl. It is slow drying & some people are allergic to it. Olive oil is often used too but any vegetable-based oil can go rancid & it tends to quicker than a nut oil. Most oils face the same issues. 'Butcher Block' oils contain a mixture of oils, usually a citrus oil in a mineral oil base plus others or even wax. These are generally safe to use, but you need to check the ingredients carefully & run them by any guests. About the only completely safe & inert oil is Mineral oil, but it never dries & too much of it has a purgative effect. All oils must be reapplied on a regular basis after washing the bowl gently with soap & warm water & then drying fully, especially right after use.
At home, I use a Maple bowl with polyurethane on it as a fruit bowl & an Ash bowl finished with wax for candy, usually wrapped but we'll put M&M's in it too. I'll sometimes make unfinished bowls for people & how they want to finish or use them is up to them.