Harissa chicken burgers

Ingredients

• 450 grams ground chicken
• 1 teaspoon finely chopped fresh rosemary
• 1/2 teaspoon salt
• 1/2 teaspoon black pepper
• 2 tablespoons extra virgin olive oil, divided
• 1 tablespoon harissa paste
• 4 thick slices crusty bread
• 1 tomato, sliced