There are several alternative methods you can try. Here are some options: 1. Create a slurry by mixing cornstarch with a small amount of cold water until smooth. Towards the end of cooking, gradually add the slurry to the chowder while stirring constantly. Cook for a few minutes until the chowder reaches the desired thickness. 2. As the chowder cooks, use a potato masher to gently mash some of the cooked potatoes against the side of the pot. This will release starch from the potatoes, naturally thickening the soup. 3. Blend a portion of the cooked vegetables (like potatoes, carrots, or corn) with a bit of the broth until smooth. Stir the purée back into the chowder to thicken it while adding extra flavor. 4. Instead of flour, you can create a roux-like mixture using alternative thickeners like rice flour or tapioca starch. Mix the chosen thickener with a small amount of cold water until smooth, and then add it to the chowder gradually while stirring.