Position an oven rack in the middle of the oven and preheat the broiler.
Put the steaks in a wide, shallow bowl. Add the soy sauce, oyster sauce, oil, and pepper and turn to coat them evenly. Cover and refrigerate for 1 hour.
Cut the cherry tomatoes, garlic, and shallot on a baking sheet and broil, turning
often, until charred in spots and softened, about 5 to 7 minutes. Remove from the
broiler and let cool until they can be handled. Peel the garlic and shallot but leave the
tomatoes unpeeled. Put the garlic in a bowl and press with the back of a spoon until
reduced to a paste. Add the shallot and mash with the spoon until it breaks down into
small pieces. Add the tomatoes and cut into chunks with edge of the same spoon.
Stir in the fish sauce, lime juice, pepper flakes, sugar, chopped cilantro, and sawtooth
coriander; set aside.
Prepare a hot fire in a charcoal or gas grill. If using charcoal, allow the charcoal to
develop a gray ash before you start grilling. Oil the grate with vegetable oil. Alter-
natively, heat a well-oiled stove-top grill pan over high heat until hot or leave the
broiler on and oil a broiler pan. Cook the steaks, turning them once halfway through
the cooking, until they are medium-rare to medium. The timing will vary depend-
ing on which cooking method you are using. If possible, test if they are ready with
an instant-read thermometer, which should register 140°F to 150°F, the ideal level of
doneness for this dish. Transfer the steaks to a cutting board, tent with aluminum foil,
and let rest for 10 to 15 minutes.
Transfer the sauce to a small serving bowl and place it on the center of a large plat-
ter. Cut the steaks against the grain into slices 1⁄4 to 1⁄2 inch thick and arrange them
around the sauce bowl. Arrange the cucumber and tomatoes on the side of the platter.
Sprinkle the whole cilantro leaves over the beef and serve immediately.