It can be left out or you can use garlic powder.
Onion salt tastes like "salty onion". Onion powder just tastes like "onion". I use both onion and garlic powder a lot, but have never used either onion salt or garlic salt, so I can use salt independently (control the amount).
there isn't one, for onion powder is a powder
You could use green onions or onion powder.
If I not have time then I mix powder of onion
there isn't one, for onion powder is a powder
I use onion powder and a little garlic powder when frying them.
You can make your own onion powder easily by dicing onion finely and drying in a single layer at 150C (use oven or dehydrator). When they are dry and crumbly they can be turned to powder using a blender or mortor/pestle.
1/8 teaspoon onion powder equals 1 tablespoon minced onion also read as this: 1/8 teaspoon onion powder equals 1/16 cup of minced onion
Onion salt contains salt also whereas onion powder only contains powdered onion.
Leeks have a flavor that is similar to onions, and it is possible to get leek soup mix (although it is not nearly a widely distributed as onion soup mix) which can be quite delicious. Beyond that, there are lots of soup mixes, experiment and find one you like.
lotion then powder?