How to Make It
In a medium nonreactive baking dish, rub the flank steak with the chili-garlic sauce. Top with the sliced yellow onion, rosemary and thyme sprigs, garlic and 1 tablespoon of the olive oil. Season generously with salt and pepper; rub the seasonings into the steak. Let marinate at room temperature for 1 hour or refrigerate overnight.
Meanwhile, preheat the oven to 375°. In a small baking dish, toss the shallots with 1 tablespoon of the olive oil and 2 tablespoons of the sherry and season with salt and pepper. Roast the shallots for 25 minutes. Add the water to the dish and bake, turning occasionally, until caramelized and softened, about 25 minutes longer. Let cool. Raise the oven temperature to 400°.
Transfer the shallots and any pan juices to a blender. Add the sherry vinegar, mustard, thyme leaves and remaining 2 tablespoons of sherry; process until smooth. With the machine on, add the remaining 1/2 cup of olive oil and the canola oil and process until emulsified. Season with salt and pepper.
In a small baking dish, toss the red onions with 1/2 cup of the shallot vinaigrette and season lightly with salt and pepper. Roast for about 30 minutes, turning occasionally, until the onions are softened and caramelized in spots. Let cool, then separate the onion layers.
Meanwhile, light a grill or preheat the broiler; oil the grill grates. Discard the yellow onion and herb sprigs and grill the steak over a medium-hot fire, or broil, for about 13 minutes, turning occasionally, until charred in spots and medium rare. Transfer the steak to a cutting board and let cool completely, then thinly slice the meat across the grain.
In a large bowl, toss the frisée with the cherry tomatoes, parsley and roasted red onions. Add the sliced steak, blue cheese and 1/2 cup of the shallot vinaigrette. Season with salt and pepper, toss gently and serve.
Grilled Chili-Steak Salad Sandwich Variation: Prepare the recipe through Step 5 and toss the frisée with the parsley, roasted onions and 1/2 cup of the vinaigrette. Grill 12 slices of country bread. Arrange tomato slices on half of the grilled bread and top with the frisée salad and blue cheese. Layer the grilled steak over the salad, close the sandwiches and serve.