Soak snow peas in a large bowl of ice water for 10 to 20 minutes (longer is fine too). Drain and pat dry with a towel.
Gather the peas in small stacks at a time and cut them lengthwise into thin ribbons.
Chop walnuts into rubble-sized pieces and place in a large bowl.
Add olive oil, lemon juice, ½ to 1 teaspoon kosher salt (to taste), many grinds of black pepper, and pepper flakes to taste (I use ½ teaspoon). Whisk to combine.
Add snow peas and toss until the vegetables are coated.
Add avocado and gently toss until combined. Eat right away.
