Betty Crocker has a simple sourdough bread starter recipe that uses quick-active dry yeast for convenience, while The Kitchn offers a good scratch-made starter recipe with equal parts flour and water. The addition of yeast and sugar eliminates the need for daily feedings, but may require longer to ripen.
To make Betty Crocker's starter recipe, stir 1 1/2 teaspoons of dry yeast into 4 cups of lukewarm water until the yeast dissolves. With an electric mixer, beat 4 teaspoons of sugar, 3 cups of all-purpose or bread flour, and the water solution for one minute on medium speed. Loosely cover the container and let the mixture stand at room temperature for at least one week. The starter is ready when it is bubbly with a strong, sour smell.
The sourdough starter recipe from The Kitchn requires attention every day, but it is usually ready to use within five days. Combine equal amounts of filtered water and all-purpose or whole grain flour, based on weight. The Kitchn recommends 4 ounces of each, or 1/2 cup of water and 3/4 cup plus 2 tablespoons of flour. Stir the mixture until smooth, cover loosely and store in a warm, dry location. The next day, add 4 ounces of water and flour to the starter and mix well with the existing dough. Repeat this procedure each day until the starter is bubbly with a pungent smell and ready to use, which usually takes about five days.