How to Make It
Light a grill. In a small bowl, combine the 1/4 cup of extra-virgin olive oil with the lemon juice and season the dressing with salt and black pepper.
Grill the torpedo onions or shallots over moderately high heat, turning a few times, until charred on the outside and just tender within, about 20 minutes. Transfer the onions to a bowl, cover with a damp cloth and let steam for 15 minutes. Peel the onions and trim the ends. Put the onions in a large bowl and keep warm.
In a bowl, drizzle the squid bodies with olive oil and season liberally with salt and pepper. Grill the squid over high heat until it is lightly charred and tender, about 1 minute per side. Transfer the squid bodies to the bowl with the grilled onions. Repeat with the tentacles.
Add the sorrel leaves and the dressing to the onions and squid and toss to combine. Season the salad with salt and pepper. Arrange the salad on 4 plates and serve right away.