Heat the oven to 350°F.
Make the matzah croutons, see recipe below.
Toss the potatoes with 2 tablespoons of the olive oil, salt and pepper. Roast at 350° for 45 minutes, until fully cooked and browned.
Put the potatoes in a large mixing bowl. Add the olives, cucumbers, tomatoes, parsley, romaine, eggs, feta, lemon juice, harissa, the remaining 2 tablespoons of olive oil and the cumin and gently toss together.
Just before serving, add the matzah croutons to the salad, and toss once more.