Festive Christmas salad

Ingredients

• 8 ripe plum tomatoes
• 6 celery stalks
• 3 yellow, orange and red bell peppers
• 1 small red onion
• 2 170-g jars marinated artichokes
• 2 clementines or oranges
• 1 cup kalamata olives
• 1/2 cup coarsely chopped dill
• 1 large lemon
• 1 tbsp granulated sugar
• 2 tsp Dijon mustard
• 2 large garlic cloves , minced
• 2 tsp dried dill
• 1/2 tsp dried basil
• 1/2 tsp salt
• Freshly ground black pepper
• 1/3 cup olive oil