French fries are the classic side chick to the typical burger, fried chicken, or whatever item you get when you roll into a fast food joint. Across the spectrum, it's difficult to find a fry that everybody dislikes in the industry. However, it's well known that drive-thru giant McDonald's has fries that are more craved than anyone else's.
Why is that? Well, if you take a dive into the ingredients that go into the crispy spuds at each chain, you'll notice that McDonald's has one key flavoring agent that makes them unique amongst major fast food brands: natural beef flavor.
On their website, McDonald's states that this ingredient starts out with hydrolyzed milk and hydrolyzed wheat. What hydrolyzed refers to is a specific type of chemical reaction where bonds within the food are broken down with the assistance of water. Both are proteins that get broken down into compounds that release meaty and savory flavors when you eat them, giving an extra punch of umami to the already salty and starchy fries. The result is the elevation to a level of flavor that puts McDonald's fries out of the reach of its competitors in terms of deliciousness.
It does mean, unfortunately, that McDonald's fries aren't vegan, because the flavor is being sourced from milk. It also means that you'll be shoving them in your face faster than the time it took to go through the drive-thru to obtain them.