Place barley, soaking liquid and a pinch of sea salt in a medium pot. Bring to a boil, reduce heat to a light simmer and cover. Cook for 50-70 minutes. It’s done when the grain is fairly soft, there is no liquid left and the bottom of the pot is mostly dry. A grain salad is not very appealing if the grain is wet.
When the barley is done cooking, I like to spread it out on a baking sheet or a big bowl so any extra moisture can evaporate. Set aside.
While the barley cooks, place the sliced red onion in a small bowl and sprinkle the umeboshi vinegar on top. Mix well and set aside. This will slightly pickle the onion making the flavor less harsh.
Prepare the vegetables. Wash and trim the ends off the green peas. Cut each one in 2-3 slices. Wash the asparagus, cut the woody ends off and slice the rest into 2” pieces.
Bring a medium size pot with 4” of water to a low boil. Blanch each vegetable separately, starting with the peas. Leave each vegetable in only until bright in color and remove and spread out immediately onto a plate so they stop cooking. Immediately after blanching, place the red cabbage on a separate plate and sprinkle with a little brown rice vinegar to preserve the bright color.
Place the barley in a bowl and add all the other ingredients. Mix well. Taste and add a little more umeboshi vinegar or brown rice vinegar if desired. Or stir in some sauerkraut.