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Sliced flank steak with chimichurri-inspired butter sauce on top, paired with corn on the cob and roasted tomatoes.

Chimichurri-Inspired Herb & Garlic Butter Sauce

A butter sauce built on chimichurri's classic flavor base — parsley, oregano, garlic, red wine vinegar — but mounted with cold butter instead of finished with oil. Same rough-chopped, bold character as the original; a smoother, clingier body from the French technique underneath. Served over grilled flank steak.
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Prep Time 15 minutes
Cook Time 15 minutes
Total Time 30 minutes
Servings: 4
Course: Main Course, Sauce
Cuisine: French-inspired
Ingredients Method Notes

Ingredients
  

For the Sauce
  • 3 tbsp fresh parsley chopped
  • 1 tbsp fresh oregano chopped (or 1 tsp dried oregano)
  • 3 tbsp red wine vinegar
  • 1/2 tsp red pepper flakes
  • 3 cloves garlic
  • salt and pepper to taste
  • 8 tbsp cold butter cut into small pieces
For the Steak
  • 1.5 - 2 lbs flank steak
  • neutral oil for the grill grates
  • salt and pepper, generously

Method
 

  1. Preheat the grill to medium-high, 450–475°F, lid down, for a full 10–15 minutes before the steak goes on.
  2. Season the flank steak generously with salt and pepper.
  3. Lay the steak on the grates and sear undisturbed for 4–5 minutes. Flip once and sear the second side for another 4–5 minutes. Total cook time is under 10 minutes.
  4. Pull the steak off the grill once it reads 130–135°F for medium-rare (it will climb a few degrees as it rests). Let it rest while you build the sauce.
  5. Rough chop the garlic, parsley, and oregano — keep the texture coarse, not smooth.
  6. In a small saucepan over low heat, warm the red wine vinegar, red pepper flakes, salt, and pepper. This is a gentle warm-through, not a reduction.
  7. Mount the cold butter into the vinegar base a few pieces at a time, whisking constantly over very low heat. Lift the pan off the burner if it starts moving too fast — the same heat-control move used throughout the series.
  8. Once the butter is fully incorporated, pull the pan off the heat and let it sit for 20 seconds to cool slightly before adding the herbs.
  9. Fold in the raw garlic, parsley, and oregano gently — no heat, texture stays intact.
  10. Slice the steak against the grain, cutting across the muscle fibers.
  11. Fan the sliced steak on a plate and spoon the sauce generously over the top.

Notes

Why This Works: Traditional chimichurri is oil and vinegar sitting loosely together — it never truly combines, so it slides off whatever it's poured over. This version borrows chimichurri's flavor base but rebuilds it using the same mounting technique behind this series' beurre blanc and brown butter sauces: cold butter whisked in gradually so it emulsifies instead of just melting. The result clings to the steak instead of running off, trading a little raw bite for real body.
If your sauce looks like it's about to separate: pull the pan off the heat immediately and keep whisking off the burner until it comes back together, then return it to low heat to finish mounting the remaining butter.