Heat a grill to medium (350° to 450°). In a small bowl, combine 1 tbsp. oil with the cayenne. Rub romaine with oil mixture. Grill, turning once, until slightly softened and streaked brown, 5 to 6 minutes total. Arrange romaine cut side up on a platter.
Whirl remaining 2 tsp. oil, the yogurt, lime juice, avocado, garlic, cilantro, salt, and 2 1/2 tbsp. water in a food processor until smooth. Spoon dressing over romaine and sprinkle with cheese and green onions.
This salad was outrageous!!! My husband & I had a small dinner party Saturday night with a Spanish Tapas theme. We ate olives, piquillo peppers stuffed with goat cheese, marinated mushrooms,marcona almonds & pollo al ajillo (chicken wings sauteed in garlic & sherry wine) for appetizers, then served this salad with grilled chorizo & clams (see Cooking Light recipie from June 2011). I dont know which was the bigger hit because the salad accented the smoky, spicy clams so well. My husband was still raving the next day. Gonna make this a keeper!!!