In the bowl of a food processor, pulse the parsley, cilantro, mint, Herbes de Carmel, scallions, garlic, and shallot until finely minced but not pasty and liquidy, 20 to 25 pulses.
Add the jalapeño, olive oil, lemon juice, lemon zest, and salt and pulse 5 more times. Divide the mixture in half.
Create 8 to 10 skewers by threading the tomatoes, onions, and fish on the skewers in any order you like. Arrange the skewers on a rimmed baking sheet and brush them with half the herb mixture.
Clean, lightly grease, and preheat a grill (or a flat griddle or grill pan, to allow the skewers to lie flat) over medium-high heat.
Working in batches if using a grill pan but all at once if on a grill, grill the skewers, turning once, until the fish is cooked through, 3 to 4 minutes per side. Serve the kebabs with the remaining green sauce.
