Prepare the grill or grill pan.

Brush eggplant slices with olive oil and season with salt.

Grill eggplant until tender and lightly charred, about 6 minutes, turning once.

Cool the eggplant, then cut into 3/4-inch pieces.

Toast pine nuts in a skillet over medium heat until golden, about 4 minutes.

Cool the toasted pine nuts.

Combine pine nuts, basil, and garlic in a food processor and pulse until finely chopped.

With the machine running, slowly add 1 cup of olive oil to create a smooth pesto.

Add soy sauce to the pesto and pulse to blend.

Season the pesto with salt.

Cook soba noodles in boiling salted water until al dente, about 4 minutes.

Rinse the noodles under cold water and drain well.

Toss the soba noodles with the pesto until evenly coated.

Add the grilled eggplant, halved cherry tomatoes, radish wedges, cucumber slices, and most of the mint leaves to the salad.

Toss the salad well.

Season the salad with salt to taste.

Garnish with the remaining mint leaves and serve immediately.