How to Make It
Preheat oven to 400°F. Boil the potatoes in salted water until fork-tender, 15 minutes. Remove with a slotted spoon and set aside.
Bring the cooking liquid back to a boil. Add the sugar snap peas and cook, 3 minutes. Drain and rinse. Cut in half and reserve.
Stir together the mint, sour cream, lime zest, lime juice, 2 tablespoons of the olive oil, 1 teaspoon of the salt, ½ teaspoon of the pepper, and 1 tablespoon water in a medium bowl. Toss together with the potatoes, radishes, and sugar snap peas, stirring to coat.
Heat the remaining olive oil in a large ovenproof skillet over medium-high. Sprinkle the remaining salt and pepper over the steak. Cook until an instant-read thermometer inserted in the thickest part of the steak registers 130° F, 4 minutes per side for medium-rare. Let rest 5 minutes, then slice against the grain. Serve with the potato-radish salad.