Method FOR THE SLAW
1. Toast the pumpkin seeds in a small skillet over medium heat, about 3 minutes. Pour into a bowl. Add the jicama, apple, sesame seeds, sugar, and lime juice. Toss well. Cover with plastic wrap and refrigerate until cold, about 1 hour. Garnish with chopped scallions or cilantro just before serving.
FOR THE FISH
2. Season the fillets with salt and half of the cilantro. Set aside while you make the sauce.
3. Heat a grill pan over medium-high heat. Rub the garlic and poblanos with olive oil and grill, turning, until the garlic is slightly charred (about 5 minutes) and the chiles are blistered all over
(about 10 minutes). At the same time, grill the limes, cut side down, until charred, about 5 minutes.
4. When they’re cool enough to handle, peel the garlic and drop it into a food processor. Stem and seed the poblanos and give them a rough chop. Add them to the food processor, along with the avocado and remaining cilantro. Squeeze in the lime juice. Process to make a fairly smooth sauce. Taste and season with salt.
5. Heat the grill pan over medium-high heat. Oil the pan. Brush the fish with oil and grill, skin side down, until the fish is almost cooked through, about 8 minutes. Turn the fish and grill for 1 minute.
6. Divide the slaw among four dinner plates. Top with the fish and spoon on the sauce.
Notes Jicama and apple make a great slaw. The crunchy texture and mild flavor make it a perfect foil for sea bass—particularly when the fish has that tasty char that comes from grilling.