I really liked this recipe. The spinach/cheese filling was simple yet very tasty. I cut actual pockets in each tenderloin instead of slicing them lengthwise. I find the filling is easier to contain that way. I simply closed each pocket with a couple of skewers. I find that using kitchen twine tends to let the filling ooze out too much. If the weather isn't cooperating for grilling you can cook this in the oven (425F for about the same amount of time should be sufficient).