In most recipes, olive oil can be substituted for butter at a 3:4 ratio by volume. For example, if the recipe calls for 1 cup (225 grams) of butter, you can replace it with 3/4 cups (180 ml) of olive oil.
Don't just break out the sour cream for nachos and baked potatoes—use it as a mayo substitute, too! Sour cream is similar in texture and flavor, and will make your salads and slaws just as creamy. Use hummus as a sub for mayo in sandwiches, or use in combination with another ingredient in dressings and salads.