Oftentimes, before cooking a dish, mise en place is a technique used by chefs all over the world for enjoying the kitchen art without having to hunt for ingredients amidst cooking. While onion powder or granulated onion is readily available, if you are short of it, use an onion powder substitute from the list below and continue cooking that delectable dish.
Onion Powder Substitutes
A whole onion is a good onion powder substitute. Other alternatives include onion flakes, onion salt, grated onion, shallot, scallion, and vegetables like celery and fennel. 
A whole onion is a fresh substitute for onion powder in your recipe. The standard quantity to follow is 3 tablespoons of chopped onions for 1 teaspoon of onion powder. Using raw onions can also mean that you may have to bite on the pungent taste, so here is a quick tip; for a cooked dish, use onions as the cooking process will mellow the taste; for dips, curries, creams, or casseroles, select a sweet variety of onion, like Bermuda, as it has a milder taste.
In absence of onion-related substitutes, don’t hesitate to grab some fennel of celery bulbs for adding the aromatic flavor to your curries, stews, and soups. These veggies not only form good onion substitutes, they also add an additional texture and flavor to your dish.
Onion flakes are the dehydrated form of onion and they have a mellow flavor. Your New York style pizza sauce will taste heavenly with these flakes. You can also use a processor to crush these flakes if you are looking for a texture like onion powder. They also make a great granulated onion substitute.
Onion salt is a combination of salt and onion powder. Using it in your recipe will replace both onion powder and salt. Marinades, dips, and rubs taste best when prepared with onion salt.
Grated onions are the best substitute for onion powder if you are preparing curries, dips, sauces, or salsa. Grated onions comprise nearly 85% water, which is actually an advantage while preparing recipes that require water. For making onion paste or onion juice, you just have to process grated onion (add some water for onion juice) and there you have another onion powder substitute.
While making salads or Asian recipes, scallions can perfectly blend in by being a great substitute for onion powder. They add a mild and crunchy flavor to your dish.
Garlic salt or garlic powder can be used in marinades or rubs as a substitute for onion powder for the spicy flavor. The taste may differ but garlic powder has its own unique flavor that makes any preparation delectable
You can use shallots as an alternative to onion powder. They can be used in preparing various dishes if your galley is out of onion powder.
There are many other food items to complement your dish in absence of onion powder and its close substitutes. 
- Mushroom (for an umami flavor)