It started with a herb garden doing better than expected, which sounds like a good problem until you are standing there looking at more rosemary and thyme than any household could reasonably use before it turns. So I started drying things down and making herb salt. Once I was doing that, garlic was the obvious next step. And once I was doing that, onion was right behind it.
That was the beginning of a habit I have not stopped.
The case for making your own is a couple of things stacked on top of each other. The most obvious is that you know what is in it. A lot of store-bought onion powder has additives and anti-caking agents, and even the ones labeled 100% onion powder leave you guessing about what those onions were sprayed with. When I buy organic onions from the store or a farmer at my local market, I know exactly what I am putting in my food and what I am not. That matters to me.
The second thing is waste. Most people throw away the onion pieces that do not make it into the recipe. The papery layers, the ends, the bits that get trimmed off. Those go straight onto a small baking tray at my house instead of in the trash. When the tray fills up, I powder it using a spice grinder. That is the whole system. And the same exact process works for garlic, which means one habit gives you two homemade spices from ingredients most people throw away.
The container it goes into is a four-compartment condiment bar. It was designed to hold garnishes at a bar. I use it for the spices I reach for constantly while cooking. Each compartment has its own little spoon and the whole thing sits right next to my stove. I flip the lid, grab what I need, and keep moving. It was designed for lemon wedges and cocktail cherries. That is neither here nor there. A good tool is a good tool.
Nothing about this required buying anything new. I already had everything I needed. The only thing it cost me was the habit of reaching for the trash instead of the tray.
From The Field: Before something hits the trash, ask if it has one more job in it first.
This is what we use and what works for us. It is not medical advice, just lived experience. Start small, use good sense, and do what is right for you.