I sautee an onion and diced carrot, and salt until carmalized, add in a clove of garlic, cook for another minute. Then add some thyme and about 1/4 teaspoon of cardamom, pepper. Cook another minute until fragrant then add a tablespoon of tomato paste, cook another minute, then add your canned tomatoes, and some water. I just guess at amounts, but a ration of 2:1 for tomatoes to water/ broth is a good start. You can add more water later if too concentrated. Cook about 30 min, then purée. Add more salt to taste and some heavy cream to whatever level of richness you like.