Cut your avocados in half and remove the pit.
In a small bowl, mix the tuna, mustard, lemon juice, and hot sauce. Mix until well combined. Give it a taste and adjust the ingredients as needed, adding salt and pepper, if needed.
Spoon the tuna mixture equally into each avocado half.
Garnish with blue cheese and scallions or chives, if desired.
Eat immediately or store in your refrigerator 2-3 days.