Step 1

Place a rack in upper third of oven; preheat to 350°. Spread out walnuts on a rimmed baking sheet and toast, tossing halfway through, until golden brown, 8–10 minutes. Let cool, then crush into large pieces with a flat-bottomed measuring cup or glass.

Step 2

Meanwhile, heat 2 Tbsp. oil in a large skillet, preferably cast iron, over medium-high. Cook peppers, shaking pan and turning peppers occasionally, until skins are lightly charred and flesh is tender, 6–8 minutes. Transfer peppers to a cutting board and let cool slightly. If peppers are large, cut in half lengthwise.

Step 3

Combine ricotta and 2 Tbsp. oil in a small bowl; finely grate zest from lemon over and mix well. Season lemon ricotta with salt. Set lemon aside.

Step 4

Combine peppers, cucumbers, mint, and half of walnuts in a large bowl. Cut reserved lemon in half and squeeze juice into bowl. Drizzle in 2 Tbsp. oil, season with salt, and toss to coat.

Step 5

Transfer pepper mixture to a platter along with any juices in the bottom of bowl. Dollop lemon ricotta over and top with remaining walnuts. Drizzle with more oil and season with black pepper.