Thoroughly rinse produce and pat dry. Place a colander in the sink. Mince chives. Trim ends on green beans. Peel russet potatoes and cut into 1" cubes and add to small pot with enough cold water to cover. Combine wasabi powder with 2 tsp. water in a small bowl and mix to form a thick paste. Rinse steaks, pat dry, and season with a pinch of salt and pepper.

Bring pot with diced potatoes to a boil, add a pinch of salt, reduce to a simmer, and cook for 20 minutes or until potatoes are tender. Drain in colander and return to pot. Mash with a potato masher or fork. Add milk, half of the butter, and half of the wasabi (to taste). Taste and add more if desired. Season to taste with salt. Wasabi can be potent, so taste the potatoes, and let sit on your tongue for a bit before deciding if you want to add more.

In a small bowl, combine remaining butter, miso, chives, sherry vinegar, and a pinch of salt and pepper. Mix until well combined and set aside.

Heat a medium pan over medium-high heat. Add 1 tsp. olive oil and allow to heat until nearly smoking. Add steaks and sear on first side for 3-4 minutes. Flip onto second side and continue cooking 4 more minutes to desired doneness, or until internal temperature reaches 145 degrees. Transfer steaks to a plate and wipe out pan. Make sure steaks rest at least 5 minutes. Return pan to heat.

Add beans to pan and cook until lightly seared on all sides. Add 1 Tbsp. water and a pinch of salt and pepper. Continue cooking 1 more minute or until beans are tender.

Add a serving of wasabi mashed potatoes to plate. Place a serving of beans next to potatoes and lean steak on both. Top steak with miso-chive butter and serve.