Toss the chicken with the soy sauce, 1 T. of the mayo and the sliced shallot. Cover and let marinate in the fridge for about 1 hour.

In another bowl, mix the sliced carrots with the pickled onions and their liquid and let stand at room temperature for about 1 hour.

Heat up a grill pan on high heat. Grill the chicken until charred and the chicken is cooked through - about 2 minutes per side. Put the shallots on after you flip the chicken. If you add the shallots right away, they will get too done.

Spread the mayo on the cut sides of the toasted baguette and then spread with Sriracha (to taste -- it's spicy). * I actually like to make a mixture in a bowl of the mayo and Sriracha, then spread it onto the bread. On th bottom half of the baguette, layer the carrots, pickled onions and sliced cucumber. Top with the grilled chicken and shallot slices. Lay the cilantro sprigs, if using, over the chicken and close the sandwich.

Cut the sandwich crosswise into 6 pieces and serve!