- In a glass dish or in a sealable plastic bag, combine all the ingredients. Add the meat and toss to coat. Cover the dish or seal the bag and refrigerate for about 6 hours or overnight. Turn over a few times, if possible.
- Preheat the grill, setting the burners to medium. Oil the grate.
- In a large bowl, brush the celery with the oil and vinegar. Season with salt and pepper. Grill for 15 to 20 minutes, turning regularly, until the celery is al dente. Set aside in a warm dish. Increase the temperature of the grill to high.
- Meanwhile, drain the meat. Keep the marinade for the sauce. Grill the meat for about 3 minutes per side, depending on its size, for rare or until the desired doneness. Set aside on a plate. Cover and let rest for 5 minutes.
- In a saucepan, off the heat, dissolve the cornstarch in the marinade. Bring to a boil and simmer for 1 minute. Adjust the seasoning. Thinly slice the meat and drizzle with the sauce. Serve with the grilled celery.