In a large pot, melt butter over medium-low heat. As it melts, you'll notice a rich, buttery aroma filling your kitchen. This step is essential as it forms the flavor base for the soup.
Add the celery, onion, and carrot to the pot. Stir them gently and sauté until the vegetables become soft, about ten to fifteen minutes. You'll see the onions turn translucent, and the carrots soften, releasing their natural sweetness.
Sprinkle flour over the sautéed vegetables. Stir well to combine, ensuring that the flour coats the veggies evenly. This will help thicken the soup later on.
Next, pour in the diced tomatoes, sugar, basil, marjoram, and your choice of broth. Stir everything together to combine. You'll notice the vibrant red of the tomatoes mingling with the other ingredients, creating a colorful mixture.
Cover the pot and let the soup simmer for thirty to forty-five minutes. This allows the flavors to meld beautifully. Keep an eye on it, stirring occasionally to prevent sticking.
Once the time is up, take your immersion blender and carefully puree the soup until smooth. If you don't have one, transfer the soup to a regular blender in batches, being cautious as it will be very hot!
After blending, pour the smooth soup back into the pot. This is where the magic really happens!
Now, stir in the half and half and add the curry powder. Mix well and remember NOT to boil the soup after adding dairy, as this can cause it to curdle.
Finally, serve the soup hot in bowls. You can garnish with fresh herbs or a drizzle of olive oil if desired. Enjoy each creamy spoonful of your delicious Easy Tomato Bisque!