Grate 1/2 teaspoon lime peel and squeeze 2 tablespoons juice from the lime.

Toast walnuts in a skillet on medium heat for 5 minutes, stirring until fragrant.

Set the toasted walnuts aside to cool.

In a food processor, combine toasted walnuts, fresh basil leaves, Thai sweet chili sauce, water, lime peel, lime juice, and salt.

Blend the ingredients until a smooth pesto consistency is achieved.

Store the prepared Thai pesto covered in the refrigerator for up to 2 days.

Preheat an outdoor grill for covered, direct grilling on medium heat, or heat a large ridged grill pan on medium until hot.

Lightly spray plum tomatoes, yellow peppers, eggplant, zucchini, and sweet onion with olive oil nonstick cooking spray.

Place the prepared vegetables on the hot grill grate.

Cover the grill and cook the tomatoes and zucchini for 6 to 8 minutes, peppers and onion for 8 to 10 minutes, and eggplant for 10 to 12 minutes, turning over once, or until the vegetables are tender.

Transfer the grilled vegetables to a serving plate as they are done.

Sprinkle the grilled vegetables with salt.

Serve the grilled vegetables with the prepared Thai Pesto.