4 Little gem lettuce heads or 1 regular romaine lettuce head
2 small radishes, thinly sliced
12 cherry tomatoes, halved
Make the dressing: Combine the mayo, lemon juice, fish sauce, and Parm in a blender and blend until creamy, 1 minute, thinning with a drop of water if necessary to achieve a ranch-like consistency.
Make the panko crumbs: Melt the butter in a skillet over medium heat. Toss in the bread crumbs and cook, stirring, until golden, 4 minutes. Stir in the salt, remove from heat, and transfer to a plate to cool.
Finish the salad: If you’re using Little Gem lettuce (they’re like little baby whole lettuces), halve them, If you're using romaine hearts, quarter them lengthwise. Arrange the lettuce on a plate, top with the tomatoes and radishes, drizzle with the dressing and top with the panko crumbs. (Extra dressing will keep, refrigerated, for up to a week. Panko crumbs will keep sealed in an airtight container for up to 5 days.)