and weigh it down with heavy cans. Cover the exposed areas with
plastic wrap or aluminum foil and place in the refrigerator
overnight.
Make the mayo. Place the egg yolk in a bowl and combine the
½ cup canola oil and the olive oil in a measuring cup. Add a single
drop of the combined oil to the yolk and whisk it in; repeat with
another drop of oil. Keep doing that, drop by drop, and pay
attention to what’s happening in the bowl: you want the yolk to
absorb each drop of oil. It should get thicker each time. Once
you’ve added several drops, you can start including a stream of oil.
Keep whisking and watching. If at any point you see oil separated
from the thickened yolk, stop the stream and whisk vigorously
until it’s incorporated. Keep going—you can pour a thicker stream
the further along you get—until the yolk has absorbed all the oil.
Congrats; you just made mayonnaise*! Now season with salt and
add a squeeze of lemon.
Cut off squares of the reserved meat; they should be large
enough to fit on the sandwich bread. Heat a skillet on medium, add
the tablespoon of canola oil, and then add the meat, searing it until
it’s crusty and golden brown on both sides.
Place the meat on the sandwich bread (which you can toast
first, if you’re not pressing it) and top it with bacon, arugula,
tomato, and a good amount of homemade mayo. If you’re planning
to press the sandwich in a panini press, shmear the outside of the
sandwich with mayo too. Press the sandwich until it’s toasty on
the outside and eat right away.