Latkes with Clarified Butter, Cotija Cheese and Truffled Ketchup

We have almost reached that time of year.  The one where I put notations on the calendar to highlight the days of Hanukkah, and put a star on the day or days on which we intend to make latkes.  Then, all too often, end up hurtling though the entire holiday, forgetting to look at the calendar, and failing to celebrate even just one of the nights. Possibly that time of the year we end up ordering pizza on the night we were supposed to do the latkes.  Not this year.  We like the idea of celebrating Hanukkah, even if we completely fail at celebrating any of the other Jewish holidays.  I think doing one holiday makes us feel like we are keeping up tradition just a teeny tiny bit, even if it's not technically a major holiday.  However, we're not exactly traditionalists, so we find latkes a fun opportunity to try new flavor combinations we may never have thought of.  Seth got the idea for these after eating french fries with cotija cheese and clarified butter from a gourmet food truck.  They were so amazing, he thought we should put those flavors into latkes and serve them with truffled ketchup.  I'm pretty sure no phone calls will be made to a local pizza place this Hanukkah.  

Ingredients
1 pound unsalted butter
2 pounds russet potatoes
1 medium onion
1 small bunch scallions, chopped
1 egg, beaten
kosher salt and freshly ground black pepper, to taste
cotija cheese, crumbled
scallions, chopped
fleur de sel
ketchup (preferably Heinz), for serving
white truffle oil, for serving

Instructions
To clarify the butter, chop the sticks up and place in a medium pot over low heat.  Melt the butter.  After a few minutes, you will start to see foam covering the top.  Once that stops bubbling up, take off heat and use a spoon to skim off the top layer of foam.  Set a piece of cheesecloth over a mesh strainer and place over a heat-proof container.  Pour the butter through the cheesecloth and strainer into the container.  

Peel the potatoes, keeping the peeled potatoes in cold water.  Once they're all done, grate the potatoes and the onion into a medium bowl.  Once all grated, begin squeezing the water out of the shredded potatoes and onion and transferring them to a new bowl.  Left behind should be some water and, underneath, some separated potato starch.  Take out the starch and mix it back in with the grated potatoes and onion.  Add in the chopped scallions, beaten egg, and generous pinches of salt and pepper.  Mix everything together.  Form thin patties with the mixture (the thinner, the crispier), and cook in a skillet (preferably cast-iron) over medium-high heat in the clarified butter. Once one side has browned (about 3 minutes) flip and cook the other side.  As they finish, remove and place on paper towel.  Just before serving, sprinkle each latke with a liberal amount of cotija cheese and scallions.  Finish with a pinch of fleur de sel.  In a small bowl, mix just a bit of white truffle oil with the ketchup (about a 1/4 teaspoon oil per 2-3 tablespoons of ketchup).  Serve the truffled ketchup with the latkes.