Preheat oven to 425 F.
Slice onions and heirloom tomatoes into thick rings.
Add the onions to a large cookie sheet and add enough olive oil to coat top and bottom of onions.
Add a nice pinch of salt and roast for 30 min.
After 20-30 min (or until onions are completely softened), add a little olive oil to the sheet and add all the tomatoes.
Top tomatoes with more olive oil.
Add a good pinch of salt, making sure every piece gets a little bit.
Place back in oven to roast for about 45 min - 1hr or until tomatoes and onions start to char and are caramelized, flipping halfway.
When the onions and tomatoes are almost done, add pasta to a large pot of boiling, salted water. Cook until al dente (about 6-7 min). Drain pasta and add about 3-4 tablespoons of olive oil. Add pinch of salt. Give it a toss.
Cut avocado in half lengthwise and slice.
Take a large serving bowl and add pasta to it.
Add burrata and cut burrata to release cream.
Arrange the roasted vegetables, sliced avocado, and use a large spoon to add the burrata to the bowl as well.
Add a drizzle of olive oil to the burrata and a pinch of salt & pepper to the avocado. Enjoy!