Trim and slice the zucchini in half length-wise. Season generously with salt, and let sit for 15 minutes.
In a small bowl or glass jar, combine basil, mint, walnuts, vinegar, capers, garlic, chili flakes, and 1 Tbsp. olive oil. Stir to combine. Season to taste with salt.
Blot zucchini dry with a paper towel to remove excess moisture. Cut into chunks.
Heat remaining 2 Tbsp. oil in a large skillet over medium. Arrange zucchini chunks cut side-down and cook, undisturbed, for 5 mins.
Toss, and continue cooking 7 to 8 more minutes, until the zucchini is deeply golden.
Add garlic-herb mixture, turn off heat, and toss to combine. Taste and season with a pinch more salt, if needed.
Serve with extra torn herbs, if desired.
