Preheat the oven to 350 degrees F.
Place each beet on a small piece of foil, drizzle with a little of the olive oil, and then wrap in the foil. Transfer the foil packets to a baking sheet. Roast until a knife can be easily inserted into the center of the beets, 45 minutes to 1 hour. Set aside to cool.
While the beets are cooking, make your dressing: Combine the light olive oil, honey, mustard, vinegar and 1 teaspoon salt in a blender. Blend until smooth. Set aside.
In a dry skillet over medium-low heat, toast the sunflower seeds until they become fragrant and start to color slightly, 3 to 5 minutes. Let cool.
Once the beets are cool enough to handle, peel the skins off with your hands or by rubbing the beets, one at a time, between two paper towels. Cut the peeled beets into roughly 1-inch cubes and set aside.
When ready to serve, place the mixed greens in a large serving bowl. Drizzle some of the dressing over the top and toss to combine. Top with the roasted beet cubes and the crumbled goat cheese. Drizzle with a little more of the dressing and sprinkle with the toasted sunflower seeds. (Once you've added the beets, be sure not to toss the salad, as they will discolor the goat cheese.) Serve immediately.
Peeling roasted beets can be a messy job, so I like to use disposable kitchen gloves.