Combine the greens, pears and toasted pecans in a large bowl and set aside.
Preheat a 2-qt. sauté pan or 10-in. omelette or fry pan over medium-high heat until the rim of the pan is hot to the touch. Add the bacon and cook, stirring often, until crisp (3 - 5 minutes).
Add the onion, celery seed, rosemary, thyme and mustard. Cook, stirring often, until the onion is golden around the edges about 2 - 3 minutes.
Add cider vinegar, balsamic vinegar and sugar. Bring to a boil then remove from heat and incorporate oil. Season to taste with salt.
Pour the warm dressing over the salad mixture and toss.