In the bottom of a large bowl, add equal parts mustard, balsamic vinegar, and avocado oil. I used 1 tablespoon each for a salad just for me. Whisk together and add salt and pepper and fresh basil.
On top of the dressing, start dumping in all the other ingredients. Drain the tuna, and give everything a rough chop, including the spinach.
Toss when it's time to eat!