Dehydrated vegetables have some advantages over canned vegetables. The cost is generally lower, and I have heard from a unreliable source that the nutritional value of dehydrated vegetables is about the same as canned vegetables. Fresh vegetables are generally preferable. The benefit of dehydrated vegetables is no refrigeration needed and long shelf life. You can portion only what you need, unlike canned vegetables. There is no peeling or chopping required.
Generally when cooking with dehydrated vegetables, it is better to think of them as a flavor addition rather than as a meal course. Use small additions of dehydrated vegetables to other ingredients. The texture of cooked dehydrated vegetables is not that great because they are small pieces. Another reason to use them is to increase vitamin intake.
Dehydrated vegetables require a 15 minute soak in water prior to cooking. They cook in less than 15 minutes of boiling. Harder vegetables such as carrots take 15 minutes, while thinner cut vegetables such as green beans take about 10 minutes. Paper thin vegetables such as leeks and spinach take just a few minutes and do not require soaking.
The best way to use dehydrated vegetables (that I have found) is in a rice mixture. This is a main staple for me so that is what makes dehydrated vegetables attractive in my kitchen. Dehydrated vegetables also work in sauces like spaghetti sauce, if you do not use too much dehydrated vegetables. The dehydrated vegetables are cut small and some of them have a hard texture (carrots, celery) so you don't want too many of them in a sauce.
A good source for dehydrated vegetables is Harmony House. They have better quality than what I have been able to find locally. The cost is about $7 per quart jar. A single serving is about 2 Tablespoons, and a combination of a half dozen dehydrated vegetables in quart jars would last me about least 6 months. So for about $60 and a foot or two of shelf space, I can store the vegetables I need for many months, no refrigeration needed. The dehydrated vegetables do age, I have some peppers that are several years old and they have changed color but I still use them.
Some vegetables work well dehydrated and some don't. The good ones are green beans, leeks, carrots, diced tomatoes, celery, jalopenos spinach and green or mixed peppers. Leeks add an excellent flavor and can be used instead of bullion to create a broth. Carrots take a long time to cook but add good flavor. Diced tomatoes add a nice texture. Celery adds good flavor and a bit of chewiness. Jalopenos are excellent but are a spice to be added in small amounts. Spinach adds color and vitamins. Green or mixed peppers add a bit of flavor and vitamins (Vitamin addition is my theory and is not proven).
Measure dehydrated vegetables by the Tablespoon. For best results, always start a meal by sauteing a fresh onion in oil. This improves the meal a great deal because dehydrated vegetables do not break down into a sauce, they remain as little bits of food. Dehydrated vegetables work well in rice dishes, be aware that they may not work in other recipes.
My standard pressure cooker recipe:
Simmer an onion in about a Tbs of olive oil until soft
Turn off heat
2 cups water
1 cup brown rice
2 Tbs lentils
2 Tbs dehydrated green peppers
2 Tbs dehydrated diced tomatoes
1 Tbs dehydrated leeks
1/2 tsp salt
2 pinches jalopenos
ground black pepper
1 Tsp chicken bullion
SOAK 15 MINUTES OR MORE
Simmer under pressure 15 to 20 minutes or as needed for brown rice