Beef in a burned towel.
Sounds appetizing doesn't it? Okay, maybe not but it really turns out well and this is such a cool trick on the grill.
Lomo al trapo (literally "beef tenderloin in cloth") is a quite popular Colombian dish that I have been wanting to try since I read about it in Planet Barbecue! this spring. It uses "caveman cooking" which is cooking directly on the coals of a fire.
The first step is finding a suitable 16" square cloth to use. Keep in mind that this will be destroyed in the process. You want something linen like a tea towel or rolling cloth.
Wet the cloth, lightly wring it out, and lay it flat. Top it with 1/4 inch thick of coarse kosher salt. Yes, that will be a hell of a lot of salt, half a box or more. This and the cloth are going to be your protective barrier.
Now place your seasonings on to of the salt. I used fresh oregano but some of the videos and resources I reviewed also added garlic, cilantro, and black peppercorns.
Place a 12" piece of trimmed beef tenderloin at the center of one edge.
Roll the tenderloin up in the towel. Secure the ends with cooking twine and one or two places in the middle as well. The book showed doing this diagonally & tying the ends together but the other sources I looked at just rolled it up this way and it seemed easier.
Nothing I read told how hot to have your grill for this, just to use a bed of established coals. This would be quite easy just pouring a lit chimney of coals into a grill and spreading them out. End of story.
But the design of the Big Green Egg is to maximize efficiency, it doesn't burn all of the coal at once. So to get a full bed of coals, I only put a small amount of lump coal, barely up to the airholes on the fire box. I fired it up and brought the temp to 350f. I stirred the coals twice during the preheating to make sure all of them got lit so I had a somewhat even bed of coals.
Now it is as simple as placing the bundle directly on top of the coals for 9 minutes. It will start to smolder a bit, don't worry. Listen to your inner-caveman. Go draw stick figures of your successful hunt on your walls.
After 9 minutes, flip and let it go 8 more minutes. Don't be alarmed, it will be stiff and the towel will be burned.
Remove and let it cool off for 2 minutes.
Raichlen says you remove the towel and crack the salt crust off. For us, the salt and towel had fused into one protective coating that just all broke right off easily. The meat just lifted right out leaving the shell behind.
Then you just brush off any leftover bits of salt with a basting brush and let rest for 5-10 minutes.
I worried that the tenderloin had been overcooked to medium from the outer appearances, but it was cooked just to medium rare like we like it.
I was going to serve it with a fiery salsa from the book called Aji but it was too hot. Instead, I made a cream sauce by reducing a cup of heavy cream, 2 tbsp of the Aji, and 1/2 teaspoon of a mild ground red pepper and that was perfect! We served this with two Colombian side dishes from Erica at My Colombian Recipes, arroz con Coca-cola (yes, rice with Coke) and a spinach cake.
I admit I wasn't confident how this was going to turn out, but at 350f the 9 and 8 minute time frames were spot on. I wouldn't make it this way every time but it is definitely worthy of a special event or when you want to "wow" guests with this quirky presentation.