For the fries: Dissolve the salt in a large bowl of cold water and add 1 cup of ice cubes. Submerge the potato wedges and soak for 20 minutes.
Preheat the oven to 450 degrees F. Line a baking sheet with parchment paper and set aside.
Drain the potatoes and pat them dry. Toss them in the butter and season with salt and pepper. Transfer them to the prepared baking sheet and bake, tossing halfway through, until browned, about 1 hour. Add additional salt and pepper if desired.
For the feta-red pepper dip: Combine the bell pepper, feta, nuts, olive oil, honey, lemon juice, cumin, crushed red pepper, garlic, a pinch of salt and a few turns of black pepper in a food processor and blend until smooth. Taste and adjust seasonings as desired.
Top the fries with the feta-red pepper dip and serve.
To make your own roasted red bell peppers, roast at 500 degrees F until charred, about 30 minutes. Let cool, then peel and remove the seeds and charred skin.