How to Make It
Preheat grill or grill pan.
In a baking dish, combine first 4 ingredients (through lime juice). Add salmon and scallops to dish, and stir with a wooden spoon to coat all pieces. Cover and refrigerate for 10 minutes.
For the Romesco Sauce, process the almonds and garlic in a blender until coarsely chopped. Add the roasted red bell peppers, cherry tomatoes, olive oil, 1 teaspoon hot water, and sherry vinegar, blending until smooth and scraping down the sides, if necessary. Season with the salt and pepper, and set aside.
Remove the salmon and scallops from the marinade, and discard liquid. Pat dry each scallop and chunk of fish with paper towels. (This will let the outside get crisp.)
Thread each wooden skewer lengthwise with scallops, salmon, onion, red bell pepper, and poblano chile pieces.
Lightly brush grill rack or grill pan with oil. Cook skewers over indirect heat 2–3 minutes, then turn gently so that the fish doesn't break and fall into the fire. (Using a vegetable or fish basket makes it easier.) Continue to cook 2 minutes more or until salmon feels firm to the touch and scallops show light grill marks. Remove skewers from grill or grill pan.
Arrange 2 skewers on each plate, and spoon the Romesco Sauce over them, or pile the skewers on a serving platter and serve the Romesco Sauce on the side. Serve immediately.