Use a clean cutting board to assemble dressing.
Place peeled garlic clove in a small microwave-safe bowl with 1 tablespoon of water. Microwave for 45 seconds to 1 minute. Garlic should be a little soft, but still firm. This will reduce the acidity of the raw garlic, but retain much of its flavor. Remove from microwave and let it stand for 30-60 seconds.
Chop green onion (white and green portions), flat-leaf parsley, garlic, and serrano pepper right on the cutting board. Add olive oil and vinegar. Mince these items, as it incorporates the liquids. Season with salt and pepper and mix through. If dressing is too dry, add another tablespoon of olive oil to the dressing.
Slice the cooked steak, and add pieces straight onto the cutting board. Using tongs, gently toss the meat with board dressing. Serve immediately.
The meat pictured in this recipe is beef tri-tip, but this dressing can use this on all types of steaks, and beef roasts.