Preheat oven to 425.
Cut squash in half lengthwise, then crosswise. Scoop out the seeds and cut pieces lengthwise into 1/2" wedges.
Toss with 1 tbsp EVOO and sprinkle with sea salt.
Spread in an even layer onto a baking sheet.
Roast, stirring 1-2x, until tender (~30 min).
Allow squash to cool somewhat as you prepare the salad dressing (combine all ingredients and mix thoroughly).
Add spring mix, oranges, squash, and tomatoes into a large bowl. Drizzle with salad dressing (to taste) and toss to combine.