Tomato Coconut Soup

INGREDIENTS

• 2 teaspoons vegetable oil, or as needed
• 1 cup diced onion
• 1 cup diced celery
• salt and ground black pepper to taste
• 2 cups water
• 1 (16 ounce) can diced tomatoes
• 1 (16 ounce) can coconut milk
• 1 (16 ounce) can tomato sauce
• 1 (6 ounce) can tomato paste