If your squid bodies have fins (thin flaps) attached to them, slice off and discard them. Put the blade of your knife inside a squid body and carefully slice it open, cutting away from you, so you have one flat piece. Cut this piece in half lengthwise. You will have two squid pieces, shaped like two long, tapered rectangles. Using your knife, lightly score the inside of each rectangle in a crosshatch pattern, not cutting all the way through.
Repeat this procedure with all the squid bodies.
To skewer the squid, thread one rectangle, lengthwise, onto a bamboo skewer, followed by two tentacles (if using), then another rectangle.
Pick up another skewer and continue until all the squid bodies are used. (You may have some tentacles left over; you can thread them together on a skewer.) Place the skewers in a nonreactive pan.
To make the marinade, combine the parsley, cilantro, lemon juice, garlic, paprika, sambal oelek, lemon zest, salt, and pepper in a bowl and whisk in the oil. Pour the marinade over the squid, cover with plastic wrap, and refrigerate for 30 minutes.
To make the lemon vinaigrette, combine the lemon juice and shallot in a small bowl and whisk in the olive oil. Season to taste with salt and pepper. Set aside.
Fire up your grill. Remove the skewers from the refrigerator and allow the squid to come to room temperature. Shake off the excess marinade, then grill the skewers over a hot fire, direct heat, with the lid off.
Turn the skewers several times as needed, until the squid is cooked through, opaque, and charred in a few places, about 1 to 3 minutes, depending on the heat of your fire. Do not overcook, or the squid will be tough. Remove the skewers from the grill.
Put the arugula in a bowl and toss it with about 2 tablespoons of the lemon vinaigrette.
Arrange the garlic toasts on a platter. Top each toast with some arugula salad. Put two squid skewers on top of each toast and drizzle the remaining vinaigrette over the skewers. Garnish with the lemon wedges.