Tuna melts, a classic lunch staple turned keto.
Preheat oven to 350 degrees Fahrenheit. Halve zucchini lengthwise and scoop out the seeds. Slice green onion, separate white and green portions.
Place zucchini halves, cut side up, on a baking sheet. Drizzle with olive oil. Bake for 15 to 20 minutes until zucchini is tender. Remove from oven and change setting to broil.
In a small bowl mix tuna, mayonnaise, white portion of green onion, celery, salt, pepper, dill, and vinegar. Fill the baked zucchini halves evenly with tuna mixture. Top with shredded cheese. Broil for 5 to 10 minutes, until cheese is melted and tuna salad heated.
Remove from oven and serve hot. Garnish with green portion of green onion if desired.