To marinate steak: Combine lime juice, lemongrass (or lime zest), soy sauce, fish sauce, garlic, ginger, brown sugar, turmeric, coriander, cumin and pepper in a small bowl. Cut steak on the bias across the grain (see Tip) into thin, 1- to 2-inch-wide strips. Place in a sealable gallon-size plastic bag, add the marinade and turn to coat. Refrigerate for at least 2 hours and up to 12 hours.
To prepare dipping sauce: Combine onion and oil in a small saucepan. Cover and cook over medium-low heat, stirring occasionally, until soft, about 5 minutes. Stir in garlic, ginger and lemongrass (or lime zest); cook, stirring frequently and reducing the heat as necessary to prevent overbrowning, 2 minutes more. Add coconut milk, peanut butter, fish sauce, ketchup, lime juice, brown sugar and hot sauce; cook, stirring, until well blended. If necessary, thin with a little water to the desired consistency. Adjust seasoning with lime juice, brown sugar and/or hot sauce. Cover and refrigerate for up to 3 days.
To prepare cucumbers: Combine cucumber, vinegar, sugar and salt in a medium bowl. Stir in cilantro (if using). Taste and add more sugar and/or salt if desired. Set aside.
To prepare satays: Preheat a gas grill to medium heat or prepare a medium-heat fire in a charcoal grill. (No grill? See Broiler Variation.)
Remove the steak from the marinade (discard marinade). Thread onto skewers, 1 strip per skewer. Grill, turning once, 2 to 3 minutes per side for medium. (If necessary, grill the satays in two batches.)
Warm the dipping sauce, if desired. Serve the satays with the sauce and the cucumbers.
Notes: Look for lemongrass—a woody, scallion-shaped herb with an aromatic lemon flavor—in the produce department of well-stocked supermarkets. To use, trim off the root end and grassy top. Peel off the woody outer leaves. Thinly slice the softer inner stalk, then finely chop.
Fish sauce is a pungent Southeast Asian condiment made from salted, fermented fish. Find it in the Asian-food section of well-stocked supermarkets and at Asian specialty markets. We use Thai Kitchen fish sauce, lower in sodium than other brands (1,190 mg per tablespoon), in our recipe testing and nutritional analyses.
Tip: Depending on your region, skirt steak may not be something your supermarket regularly carries—call ahead to make sure it’s available or ask your butcher to order it for you. It’s usually sold in about 1-pound cuts up to 18 inches long and 5 inches wide, but just 1/4 inch thick. Before cooking, cut the steak with the grain into several portions to make the long piece more manageable on the grill or in a skillet. Once cooked, be sure to slice it across the grain for maximum tenderness. Hanger steak, flat-iron and flank steak can all be used as substitutes for skirt steak in most recipes.
Broiler Variation: Position a rack in upper third of oven; preheat broiler. Coat a broiler pan (or a wire rack set on a large baking sheet) with cooking spray. Broil the skewers, turning once, 2 to 3 minutes per side for medium.
To Make Ahead: Cover and refrigerate the peanut sauce for up to 3 days; cover and refrigerate the marinated cucumbers for up to 1 day; marinate steak (Step 1) for up to 12 hours. | Equipment: 20 to 30 (6-inch) bamboo skewers
