Preheat the oven to 350 degrees.
Bring water to a boil and cook the pasta as directed; drain and rinse with cold water.
Meanwhile, add 1 Tbsp. expeller pressed coconut or olive oil to a skillet over medium. Add celery and onions and cook until soft, about 5 to 7 minutes.
Whisk in the rice flour and stir one minute.
Slowly add the 2 cups beef broth, stirring to make smooth.
Bring the sauce to a boil and stir constantly until thickened. (This took me about 10 minutes.)
Turn off the heat on the sauce, add the mayo, salt and pepper and stir until blended.
Stir in the celery, onion and peas as well as the tuna.
Add back in the drained pasta and fold together until saucy.
Spray a 8 x 8 inch casserole pan and spread the noodle/sauce mixture in there.
Cover with foil and bake for 25 minutes. Enjoy!