Whether you’re making stew in a Dutch oven or slow cooker, it’s always a good idea to check on it during the last half-hour of cooking to make any last-minute adjustments. So if you’ve discovered that your beef stew is too watery, it’s not too late to alter its fate. Most thickening techniques will not significantly alter the flavor of your good beef stew, while a few might make it even better.
Thicken your beef stew by combining equal amounts of water and cornstarch in a bowl and then adding the mixture to the stew. Ensure that the cornstarch is completely dissolved first. As a thickening agent, cornstarch is doubly effective as flour, but give the stew time to simmer with the mixture. Alternatively, use arrowroot in the same manner as cornstarch. Arrowroot is more neutral-tasting than cornstarch, but it is more expensive, too.
Make a roux (pronounced “roo”) with equal parts flour and butter or vegetable oil heated in a small saucepan. Whisk the roux into the beef stew while the roux is warm or even cold, but not hot, for the best results. Continue to simmer and stir the stew for about 20 minutes until the roux is fully incorporated in the stew. Start by adding 3 ounces of roux for 1 quart of stew. Increase the proportion to 4 and then 5 ounces of roux for every quart of stew until you achieve the consistency you desire.
Combine 2 ounces of heavy cream with one egg yolk for every 16 ounces of beef stew in a small bowl. Pour a little bit of the heated stew into this mixture to prevent the eggs from coagulating, and then gently stir the ingredients into the stew. Add this mixture, called a "liaison," to the stew toward the end of the cooking time.
Puree some of the stew with a blender and stir it back into the stew. Alternatively, puree some potatoes, vegetables or another ingredient that will complement and thicken the stew.
Add some tomato paste or diced tomatoes to your beef stew. Tomatoes will alter the flavor, so perform a test with some stew in a small bowl before adding them to the full batch.