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Baking
1 T cornstarch, potato starch or arrowroot {for thickening} > 2 T flour
1 cup cake flour > 7/8 cup all purpose flour {same as 1 cup minus 2 T}
1 t baking powder > 1/4 t baking powder + 1/2 t cream of tartar
1 T cornstarch > 2 T flour
1 cake yeast > 1 pkg or 2 t active dry yeast
1 square unsweetened chocolate > 3 T regular cocoa {unsweetened} + 1 T butter
6 oz pkg semi-sweet chocolate chips > 2 squares unsweetened chocolate + 1/2 cup sugar + 2 T shortening
1 cup nuts > 1 cup rolled oats
Dairy
1 cup whole milk > 4 T powdered whole milk + 1 cup water or 1/2 cup evaporate milk + 1/2 cup water
1 cup sour milk > 1 T vinegar or lemon juice + milk to equal 1 cup, then let stand for 5 min
1 cup half & half > 1 cup evaporated milk
1 cup sour cream > 7/8 cup buttermilk + 2 T whipped shortening
1 cup yogurt > 1 cup sour cream
1 cup creme fraiche > 1 cup sour cream
1 cup cottage cheese > 1 cup farmer’s cheese or ricotta
1 cup butter > 7/8 cup shortening
1 egg > 2 yolks + 1 T water
Flavorings
1 1/2 cups chili sauce or ketchup > 1 cup tomato sauce + 1/2 cup sugar + 2 T vinegar
1 t dry mustard > 1 T prepared mustard
1 cup honey or corn syrup > 1 1/4 cups sugar + 1/4 cup of either water or whatever liquid is in the recipe
1 clove garlic > 1/8 t garlic powder
2 t finely chopped chives > 2 t finely chopped green onion tops
1 T fresh herbs > 1 t dried herbs
1 t fish sauce > 1 t ea Worcestershire & soy sauce
1 t Worcestershire > 1 t steak sauce
Liquids
1 cup beer or brandy > 1 cup water, white grape juice, apple cider or apple juice
1 cup chicken broth > 1 bouillon cube or 1 t chicken bouillon granule dissolved in 1 cup of boiling water
1 t instant chicken stock base > 1 chicken bouillon cube
1 cup tomato juice > 1/2 cup tomato sauce + 1/2 cup water
Rum > 1 T rum extract + enough water to make 1/4 cup
Misc
1 cup cracker crumbs > 1 cup dry bread crumbs or coarsely ground oats
1 cup currants > 1 cup other dried fruits, such as raisins, dates, etc
1 cup tahini > 1 cup peanut butter
1 T white vinegar or cider vinegar > 1 T lemon or lime juice
Note: I pulled this information for the most often needed substitutions from a number of sources. If you have a better sub or have any issues with the ones listed here, please let me know. Meanwhile, here’s the most comprehensive listing I found. Food subs