1 medium leek, white part only, halved lengthwise, sliced 1/2 inch thick and rinsed well
2 cloves garlic, minced
1 sprig fresh thyme (or 1 teaspoon dried)
1 bay leaf (preferably Turkish)
2 teaspoons olive oil
1 pound flank steak
Kosher salt and ground black pepper
1/3 cup fat-free plain Greek yogurt
1 teaspoon prepared wasabi
Chopped fresh chives or parsley, to garnish
In a large saucepan over medium-high heat, combine the broth, carrots, parsnips, turnips, leek, garlic, thyme sprig and bay leaf. Bring to a boil and simmer for 15 to 18 minutes, or until the vegetables are tender.
Meanwhile, in a large skillet over high, heat the oil. Season the steak with salt and pepper.
When the oil in the skillet is hot, reduce the heat to medium-high and add the steak. Saute until well browned on both sides and medium-rare at the center, 8 to 10 minutes total. Transfer the beef to a plate, cover loosely with foil, and let rest 5 minutes. After 5 minutes, thinly slice the beef against the grain.
In a small bowl, stir together the yogurt, wasabi and any juices from the beef plate. Season with salt and pepper. Discard the thyme sprig and bay leaf, then divide the vegetables and broth among 4 soup bowls. Arrange a quarter of the steak in the center of each bowl and top each portion with a spoonful of the wasabi cream and a sprinkle of chives.
Nutrition information per serving: 370 calories; 110 calories from fat (30 percent of total calories); 12 g fat (4 g saturated; 0 g trans fats); 50 mg cholesterol; 27 g carbohydrate; 6 g fiber; 10 g sugar; 38 g protein; 500 mg sodium.