Little gem lettuce is a smaller and slightly sweeter (and not to mention cuter) version of romaine. If unavailable, chopped romaine hearts or mini romaine hearts can be used in place of the little gem lettuce.
Add the anchovies, garlic, green onions, white wine vinegar, lemon juice, Greek yogurt, olive oil, basil, parsley, and tarragon into a blender or food processor.
Blend until the dressing is thoroughly combined and smooth, about 1 minute. Store in an airtight container and refrigerate for up to a week.
Buttered breadcrumbs:
Preheat oven to 350ºF. Toss breadcrumbs in melted butter and spread evenly in a single layer on an aluminum-foil lined baking sheet.
Season with salt and pepper then bake until golden brown and crisp, about 15 minutes.
Store in an airtight container for up to a week.
For assembling the salad:
Add the lettuce to a large bowl. Toss with 3 tablespoons of the dressing until thoroughly all pieces of lettuce are coated.
Add the radish, avocado, snap peas and breadcrumbs then toss to combine. Divide among plates and top with grated cheese.