Spiced Beef Burger With Shaved Cucumber and Beet Salad

Name: Spiced Beef Burger With Shaved Cucumber and Beet Salad
Ingredients: canola oil, for the grill; 1/2 cucumber, thinly sliced; 1 small yellow beet, scrubbed and very thinly sliced; 2 tablespoons olive oil; 1 tablespoon sherry vinegar; 2 tablespoons fresh dill; kosher salt and black pepper; 1/4 cup mayonnaise; 2 tablespoons harissa (North African chili sauce; found in the international aisle); 1 1/4 pounds ground beef chuck; 1 1/2 teaspoons ground cumin; 2 cloves garlic, pressed; 4 ciabatta rolls, split; lettuce leaves, for serving