Cook the barley: Place the barley in a large pot of water with the stock concentrate and a large pinch of salt. Bring to a boil, then reduce to a simmer for about 25 minutes, until tender. Drain and set aside.

Prep the veggies: Wash and dry all produce. Meanwhile, halve the tomatoes. Drain and rinse the great northern beans. Halve, peel, and thinly slice the shallot. Pick the basil leaves off the stems.

Cook the tomatoes: Heat a drizzle of olive oil in a large pan over medium-high heat. Add the tomatoes and cook, tossing for 4-5 minutes, until softened. Set aside.

Prep the avocado: Halve, pit, and scoop out the avocado flesh with a spoon. Thinly slice the avocado.

Make the vinaigrette: In a large bowl, whisk together 1 Tablespoon Dijon mustard and the balsamic vinegar. Slowly whisk in about 5 teaspoons olive oil. Season to taste with salt and pepper.

Toss and serve: Toss the vinaigrette into another large bowl with the drained barley, great northern beans, avocado, tomatoes, and shallot. Season with salt and pepper. Serve the warm barley salad, topped with the basil leaves, and enjoy!