Step 1

Preheat oven to 350°. Toss pumpkin seeds, sesame seeds, and oil on a rimmed baking sheet; season with salt. Bake, stirring occasionally, until pumpkin seeds are puffed and both seeds are golden brown, 6–8 minutes.

Step 2

Purée avocado, tomatillo, spring onion, jalapeño, garlic, lettuce, kale, mint, parsley, tarragon, lime juice, half of toasted seed mixture, and ¼ cup water in a blender until smooth; season with salt.

Step 3

Do Ahead: Mole can be made 1 day ahead. Cover and chill.

Step 4

Prepare grill for medium heat (or, heat a dry cast-iron skillet over medium). Toss squash, eggplant, spring onions, romaine, and oil in a large bowl to coat; season with salt. Grill vegetables, cut side down, turning occasionally, until tender and lightly charred all over, 5–10 minutes.

Step 5

Spoon some mole on a platter (you will not need all) and arrange grilled vegetables on top. Top with herbs and remaining toasted seed mixture. Serve vegetables with lemon wedges for squeezing over.