Make dressing: in a measuring cup or small bowl, whisk Dijon mustard, lemon zest, white sugar, 1/2 teaspoon each dried oregano and dried rosemary, lemon juice, and 1/2 teaspoon each salt and pepper until combined. While whisking, add oil until dressing comes together. Set aside or chill until ready to use.
Wash and prepare produce: chop head of Romaine lettuce across horizontally to create long, thin ribbons about 1/4" to 1/2" wide until you reach the end of the lettuce. Core tomatoes and cut into large chunks. If desired, peel and deseed cucumber. Cut cucumber in half lengthwise, and cut crosswise into large chunks. Thinly slice onion. Leave pepperoncini whole or deseed and cut in half. If you purchased a block of feta cheese, cut into cubes.
Prepare salad: Place lettuce on a large platter as the bed of the salad. Top with chunks of tomatoes, cucumbers, and feta. Add onions and arrange olives, pepperoncini, dolmades, and anchovies if using. Sprinkle remaining 1/2 teaspoon oregano over salad, along with salt and pepper to taste.
Pour dressing over entire salad and toss before serving, or add dressing to individual portions after serving.
Warm up pita bread in a toaster oven or over the grill, cut into wedges and serve with the salad.
You can substitute 1 pint cherry tomatoes, which I find to be a better alternative if tomatoes aren't in season. I like Spanish or Vidalia onions, but you can use red onions if you'd like.
For the dressing: depending on how large and fresh the lemons are, I like to have at least 2 available in case I need one as back-up to get more juice. Or, you could use bottled lemon juice, as well, to add to the juice that you get from the lemon.