1 lb. beef tenderloin, trimmed
and cut into 1" cubes
6 tbsp. canola oil
7 tsp. sugar
4 tsp. freshly ground black
Kosher salt, to taste
1 bunch watercress, for garnish
1⁄4 cup rice vinegar
1⁄4 cup soy sauce
1 tbsp. fish sauce
Juice of 2 limes
3 scallions, cut to 1" lengths
2 cloves garlic, finely chopped
1 medium red onion, thinly sliced
1 tbsp. unsalted butter
1. Toss the beef with 2 tbsp. oil, 1 tsp. sugar, and 2 tsp. pepper in a large bowl and season with salt. Cover bowl and set aside to let marinate at room temperature for 1 hour, or refrigerate overnight.
2. Dress a platter with watercress and set aside. In a medium bowl, whisk together the vinegar, soy sauce, 2 tsp. sugar, and fish sauce to make a vinaigrette; set aside. In a small bowl, make a dipping sauce by whisking together the remaining sugar and pepper with the lime juice; season dipping sauce with salt and set aside.
3. Drain beef, pat dry with paper towels, and discard marinade. Working in 2 batches, heat 2 tbsp. oil in a flat-bottomed wok or a 12" nonstick skillet over high heat. When oil begins to smoke, add half of the beef. Cook, flipping once, until well browned and medium rare, 3–4 minutes. Add half of the scallions, garlic, and red onions and cook, stirring constantly, until wilted, 30 seconds. Add half of the vinaigrette and butter; toss to combine. Spoon beef and vegetables over platter of watercress. Serve with lime dipping sauce.
Pairing note Slanted Door's Wine director Mark Ellenbogen recommends the 2004 Nikolaihof "Steiner Hund" Reserve Riesling ($82) from Austria's Wachau region to complement the spicy notes and rich mouth-feel of the beef; a worthy splurge.