Steak with Green Sauce

pan-seared flank steak (thinly sliced) with green spinach sauce and mashed sweet potatoes - in a cast iron skillet.

Steak and green sauce are a classic pairing! This version is inspired by Argentina’s famous chimichurri but with a twist—it’s made with spinach, garlic, balsamic vinegar, olive oil, and a blend of spices. It’s super easy to whip up in a food processor and will elevate your next steak dinner to something special!

Course Main Course

Cuisine American

Keyword steak with green sauce

Prep Time 20

Cook Time 30

Total Time 50

Servings people

Calories 733kcal

Author Julia

Ingredients

Sweet Potatoes

3 large sweet potatoes or yams
1 tablespoon olive oil
2 tablespoons salted butter room temperature
salt and coarsely ground black pepper to taste

Spinach Sauce

5 oz fresh baby spinach
1 large clove garlic
3 tablespoons olive oil
1 tablespoon balsamic vinegar
½ teaspoon cumin
1 teaspoon chili powder
¼ teaspoon salt

Steak

1 lb flank steak
1 teaspoon chili powder
½ teaspoon salt
black pepper freshly ground, to taste
3 tablespoons olive oil divided

Garnish

3 tablespoons salted butter
chopped fresh cilantro or parsley
freshly ground black pepper

US Customary - Metric

Instructions

Mashed sweet potatoes

Preheat the oven to 350 F. Wash and rub the sweet potatoes under warm running water to remove debris and dirt, pat them dry with paper towels, then slice each lengthwise in half.
Line a large baking sheet with parchment paper. Rub the cut sides of sweet potatoes with olive oil and season generously with salt and freshly ground black pepper. Place the sweet potatoes (cut sides down) on the baking sheet.
Bake for about 30 minutes (or longer), until the potatoes are soft when you poke them with the fork.
Remove the roasted sweet potatoes from the oven and let me cool slightly. Remove the skins, and mash the soft flesh with 2 tablespoons of butter in a large bowl. Set aside.

Make spinach sauce

While you roast the sweet potatoes, prepare the spinach sauce.
In a food processor, combine spinach, garlic, olive oil, balsamic vinegar, cumin, chili powder, and salt. Close with the lid.
Process/blend for about 3 or 5 minutes until the mixture is smooth. (⬆️ To see the consistency of the spinach sauce - refer to the photos above this recipe card - scroll up ⬆️).
Turn off the food processor and remove the sharp centerpiece. Using a flexible spatula, pour the sauce from the food processor into a medium-deep bowl. Set aside.

Steak

Season the flank steak on both sides with chili powder, salt, and freshly ground black pepper, using 1 tablespoon of olive oil to rub the spices in. Add more seasoning to taste.
Heat an empty large (at least 12-inch) cast-iron skillet over medium heat for 3 minutes. This allows the cast-iron skillet to heat through. Add 1 tablespoon of olive oil. Add the whole flank steak and cook on one side on medium heat for a total of 5 minutes. Move the steak slightly around the pan in the first minute so that it doesn't stick to the bottom.
Flip the flank steak over to the other side, reduce heat to low-medium, and cook for about 5 minutes or more until the steak is cooked to your liking. As a guidance, the meat thermometer should register 130°F for medium-rare, and 145°F for medium in the thickest part of the steak (FDA-recommended safe internal cooking temperature for steak is 145°F).
Remove the steak from the skillet and put it on a plate. Slice the steak against the grain into thin strips about 1-inch wide.
To the same, now empty, cast-iron skillet, add 1 more tablespoon of olive oil. Add cooked and sliced flank steak, and reheat it coating it thoroughly with the olive oil sauce (and all the juices and spices in the pan) on medium heat for a minute or two. If your steak looks too undercooked to your taste, you can cook it more thoroughly in this step. Season with salt and pepper, if needed. Remove from heat.

Assembly

Divide pan-seared flank steak and mashed sweet potatoes (warm them up if needed!) among 4 serving plates. Drizzle the steak with the spinach sauce in some spots. Top hot mashed potatoes with butter and coarsely ground black pepper.
Top with chopped fresh cilantro or parsley.

Nutrition