Bring a medium sauce pot of generously salted water to a boil for the bucatini.

• Rinse the shellfish, then drain on a paper-towel-lined plate and pat dry. Season the shrimp lightly with salt and pepper, the scallops generously.
• Finely chop, press, or grate the garlic.
• Zest and juice the lemon, keeping the zest and juice separate. [Zest and juice 1 lemon; save the remaining lemon.]
• Strip the parsley leaves from the stems; coarsely chop the leaves.

To the pot of boiling water, add the bucatini and cook until just tender, 10 to 12 minutes. Drain the bucatini, reserving ½ cup [1 cup] pasta cooking water.
While the bucatini cooks, start the scampi.

For the shrimp:
In a large frying pan over medium-high heat, warm 1 to 2 tablespoons oil until hot but not smoking. Add the shrimp and cook, turning once, until starting to turn pink but not yet cooked through, about 1 minute per side for regular shrimp, 2 minutes per side for jumbo shrimp. Transfer to a plate.

For the scallops:
In a large frying pan over medium-high heat, warm 1 to 2 teaspoons oil until hot but not smoking. Add the scallops and cook without turning until golden brown on one side and starting to turn opaque, 2 to 3 minutes. Turn and continue cooking for about 30 seconds for translucent and not yet cooked through. Transfer to a plate.

Reduce the heat to medium, stir the butter and garlic into the pan, and cook until the butter is melted and the garlic is fragrant, about 1 minute. Stir in the parsley, reserved pasta cooking water, 1 teaspoon [2 tsp] lemon zest, 1 tablespoon [2 TBL] lemon juice, and as many chile flakes as you like. Add the shrimp or scallops and bucatini, remove from the heat, and toss until the seafood is cooked through and the ingredients are combined. Season to taste with salt and pepper.
While the scampi cooks, prepare the salad.

In a large bowl, toss together the mixed greens and caper vinaigrette. Season to taste with salt and pepper.

Transfer the scampi to individual bowls and serve the salad on the side.