Spicy Thai Beef Salad with Mizuna

Name: Spicy Thai Beef Salad with Mizuna
Ingredients: For the Salad; 3/4 pound flank steak; 1/4 cup fresh mint leaves, coarsely chopped; 1/4 cup cilantro leaves, coarsely chopped; 1 shallot, sliced very thin; 1/2 pint cherry tomatoes, halved; 1/3 cup unsalted roasted peanuts; 3-5 ounces mizuna (or baby arugula); For the Dressing; 2 cloves garlic, pushed through a press; 2-3 teaspoons sriracha (or you can use minced Thai chilies); 1/2 teaspoon chili powder; 2 tablespoons sugar; 5 tablespoons fish sauce; 3 limes, juiced; 1/2 tablespoon sesame oil