Make the salad dressing by adding all the salad dressing ingredients (extra-virgin olive oil, lemon juice, lemon zest, red wine vinegar, minced garlic, mustard, dried oregano, salt, and pepper) to a small jar with a lid and shake it until the dressing is emulsified. Alternatively, you can just whisk the dressing ingredients in a bowl.

Toast the walnuts. You can do so in a dry pan over medium-high heat, toasting the walnuts for about 4-5 minutes, stirring frequently so they don’t burn. Alternatively, toast the walnuts in the preheated oven at 375°F (or 190°C) for about 6-8 minutes, keeping a close eye on them so they don’t burn. Once toasted, set them aside on a cold plate or surface to cool down before adding them to the salad.

Wash and chop the romaine lettuce, the cucumber (note 1 below), and the tomatoes. Slice the red onion thinly. Crumble the feta.

Toss all the salad ingredients with the salad dressing in a large mixing bowl. You can use two salad spoons, salad tongs, or two wooden/larger spoons to toss the salad.