Roast the potatoes: Preheat oven to 400°F. Toss potatoes with 2 tbsp olive oil, salt, and pepper. Roast for 25-30 mins.
Blend the dressing: Whisk mayonnaise, sour cream, pickles, splash of pickle juice, herbs, and spices.
Sear the steak: Season steak. Sear in a skillet over high heat with 1 tbsp oil for 4-5 mins per side. Rest for 10 mins.
Slice the meat: Thinly slice steak against the grain.
Assemble: Layer greens, warm potatoes, tomatoes, and sliced steak.
Drizzle: Top generously with pickled ranch dressing.
Notes
If you are making the pickled ranch ahead of time, store it in an airtight container in the fridge for up to 5 days. For the crispiest potatoes, ensure they are completely dry before tossing them in oil.