Quantities of Ingredients: Never worry about exact quantities for anything prepared on top of a stove. Use more or less any time. The idea is to produce a unique flavor from the combination of the flavors of the ingredients used.
When onions are sauteed, they can be anywhere from totally softened to crispy, depending on the time over high heat. Simmering in sauce does not appreciably affect the texture achieved during the sauteeing (high heat) time.
If the people you cook for will tolerate larger pieces of onion in their food here's a quicker way to dice them that is virtually tearless. Cut off the top of the onion. From the top make six cuts (like cutting a pie), but don't cut all the way through. Then just slice the onion into the skillet.
Keep your knives sharp. More people are cut with dull knives than with sharp knives. A sharp knife goes where you intend it to go, a dull knife does not. That's when you cut yourself.
Variations on quantities matter for baked dishes. If you vary quantities of items prepared in an oven, you need to adjust the cooking times.
If people you cook for are sensitive to the taste of tomatoes, it's probably the acidic taste they object to. Here are a few things you can do. 1) Add a bit of sugar to the recipe (1/2 teaspoon to 1 teaspoon per tomato). This lessens the acidic taste. 2) Let the dish cook longer. The acidic flavor of the tomatoes is lessened when the acids interact with other items in the dish.
If you add sugar to a dish cooking in a skillet, add it just before the end of cooking. The effect of the sugar still works. Adding sugar earlier requires almost constant stirring, because it will burn onto the skillet.
If someone you cook for is sensitive to the taste of green peppers, leave them out. It's better to try an altered recipe than to miss out on a dish that could be part of your regular menu just because the recipe called for green peppers.
Many recipes that call for sour cream really mean cream, not sour cream. Sour cream used to refer to cream that was no longer sweet - in other words about ready to curdle. The term exists in many recipes that have been around since before sour cream showed up in grocery stores. If a recipe calls for sour cream, try using sour cream. If that doesn't seem right in the prepared dish, try it again replacing the sour cream with cream.
Instructions on packages of pasta always give an amount of time to cook and a warning to not overcook. By the time you've cooked pasta the recommended time, it's usually already overcooked. Start testing it about 2 minutes before the time recommended on the package.