Start by cooking the quinoa on the stove. Grab a medium-sized saucepan and add the quinoa and vegetable broth. Add the lid, and cook the quinoa on high heat until a rolling boil starts. Then, turn the heat to low and allow the quinoa to simmer for 15 minutes or until all of the water is absorbed.
Remove the pan from the heat and take off the lid. Add 1/2 teaspoon of salt and fluff the quinoa with a fork. Set it aside to cool.
Make the dressing in a mason jar. Add all of the ingredients to the jar, secure the lid, and give it a shake for about 30 seconds, until it becomes a creamy, and well-incorporated dressing. Set it aside.
Rinse and drain the cannellini beans.
Chop all of the vegetables, including the cucumber, tomatoes, shallots, and arugula.
To a medium salad bowl, add the quinoa, vegetables, and 3/4 of the dressing. Using two forks, toss the salad until the dressing is evenly incorporated.
Now it's time to prepare the jars. Start by placing around 2 tablespoons of dressing at the bottom of each mason jar until the extra dressing is all used up. This is because the quinoa can soak up a lot of dressing overnight. It's nice to have a little extra dressing to toss in when you are ready to eat it.
Place the quinoa mixture into each of the mason jars until it reaches the top or is totally full. Secure the lids and place them in the fridge for at least two hours before you eat them. They are best enjoyed cold.