For the dressing:
Heat the oil in a heavy medium skillet over medium-low heat. Add the garlic, let it cook for one to two minutes and then add the herbs and saute until fragrant, about 30 seconds. Cool to room temperature. Whisk in the lemon juice. Season the dressing with salt and pepper, to taste.
For the seafood:
Prepare the griddle (medium-high heat). Pat the scallops and squid dry with paper towels and thread them onto skewers. Brush them with 2 tablespoons of the dressing. Sprinkle with salt and pepper.
Griddle the scallops and squid until just cooked through, turning once, two to three minutes per side. Cool completely. Cut the squid crosswise into 1/2cm wide rings.
Combine the rocket, carrots, bell peppers, and cannellini beans in a large bowl. Toss with 225ml of the dressing to coat.
Place one large or two medium radicchio leaves on each of four plates. Spoon the bean salad into the radicchio cups. Top with the scallops and squid. Drizzle the remaining dressing over the seafood and serve.