Add finely chopped red onions to a medium-sized bowl. Cover with cold water and let sit for 10 minutes. Drain and pat dry. Soaking helps reduce the potency of the red onions.

While red onions are soaking, cook the potatoes. Bring a large pot of water to a boil with 1 tbsp kosher salt. Add the potatoes and cook for 12-15 minutes until a fork inserted comes out with minimal resistance.

Drain and transfer the potatoes to a large cutting board. Let cool for 5 minutes until safe to touch. Cut potatoes into quarters (some in half, if smaller). Add cut potatoes to a large mixing bowl.

Gently toss potatoes with mayo, yogurt, fresh herbs, lemon juice, 2 tsp kosher salt (more or less to taste), and black pepper.