Whisk together the sour cream and the garlic. Slowly whisk in the creme, then the olive oil. Stream in the vinegar while continuing to whisk.
Whisk in the sweetener, dill, red pepper flakes, sea salt, and pepper. Stir in diced cucumber. Taste and adjust seasonings. Cover and refrigerate until ready to use. Dressing can be made up to two days ahead. Stir before serving.
Preheat grill to high heat.
Brush each half romaine head with olive oil on all sides. Sprinkle all sides with salt and pepper.
Place romaine heads on preheated grill using tongs. Grill with the top open for 1-3 minutes or until outer leaves of the romaine just start to brown. Turn and repeat for the other sides.
Serving size: 1/2 head of Romaine and 1/6th of the dressing
Fat (g): 12
Carbs (g): 1
Fiber (g): 0
Protein (g): 0
Net carbs (g): 1