1. Add all of the chimichurri ingredients (red chilis, garlic cloves, parsley, cilantro, green onions, dried oregano, 1 tsp salt, 1 tsp pepper, fresh lemon juice, red wine vinegar, olive oil) to a food processor or blender, pulse until finely chopped. Cover & refrigerate.
2. If roasting garlic for mashed potatoes: preheat your oven to 400°F (205°C). Slice the tops off both garlic heads, drizzle with olive oil, season with salt, wrap in foil, & roast for 45–60 mins, or until soft.
3. Peel & quarter the potatoes, place in a large pot & cover with water by about 1 inch. Bring to a boil & cook until a fork slides through with nearly no resistance, about 15–20 mins. Drain, & let the potatoes sit in the hot pot for 1–2 mins to dry.
4. Mash using a potato ricer or masher. Heat the cream until warm (pot or microwave). Squeeze in the roasted garlic & add 1/4 cup butter, gradually stir/mix in the warm cream. Season with salt & pepper to taste.
5. Cut steak into large bite-sized pieces, & season with 2 tsp salt and 1 tsp pepper. Heat a large skillet over high heat with a drizzle of neutral oil. Once the pan is smoking hot, add the steak (work in batches if needed). Cook until a deep crust forms, about 2–3 mins per side. Reduce heat to medium, add 3 tbsp unsalted butter + rosemary sprigs & garlic cloves (if using), baste for about 1 min.
