These mega-garlicky grilled filet mignons have been on the menu at Heaven Restaurant in Kigali since the restaurant opened. To be strictly authentic, you’ll need to know about one exotic ingredient—cassava leaves—which taste a little like cooked spinach. If you live near an African grocery store, you may be able to find canned cassava leaves—otherwise, use cooked spinach.
Step 1: Place the beef in a nonreactive baking dish.
Step 2: Make the marinade: Combine the soy sauce, red wine, honey, vinegar, ginger, garlic, and pepper in a mixing bowl and whisk to mix. Pour this mixture over the beef and marinate for as little as 4 hours or as long as overnight, turning the steaks a couple times so they marinate evenly.
Step 3: Meanwhile, make the sauce: Place the cassava leaf puree, if using, onion, garlic, cilantro, parsley, oregano, hot pepper flakes, lime juice, salt and olive oil in a food processor. Puree until smooth, adding enough olive oil to obtain a thick but pourable sauce. Correct the seasoning, adding salt and pepper to taste.
Step 4: Set up your grill for direct grilling. Brush and oil the grill grate. Drain the filet mignons well, discarding the marinade, and arrange on the grill grate. Grill until cooked to taste, 3 to 4 minutes per side for medium-rare, giving each filet a quarter turn half way through to lay on a crosshatch of grill marks.
Step 5: Transfer the fillets to a platter or plates. Spoon chimichurri sauce over each and dig in.
Cassava leaves, which are toxic unless cooked, are difficult to find in the U.S. But dried ground cassava leaves can be purchased in 9-ounce packages from the Global Food Market. As noted above, you can substitute spinach.