Preheat oven to 300° F / 150° C. Toss tomatoes with 1 tbsp of olive oil and spread out in a single layer on a baking sheet. Roast for 20-30 minutes or until tomatoes begin to burst. Remove from heat and let cool.
In a small bowl whisk together remaining 2 tablespoons of oil plus vinegar, simple syrup, garlic and pepper to taste; store in the fridge for few minutes.
Place greens in a large serving bowl. Top with roasted tomatoes and onion. Drizzle with vinaigrette; toss to coat. Sprinkle with pecans and enjoy.
Recipe by CookingGlory at http://www.cookingglory.com/recipes/meal-ideas/salads/mixed-greens-salad-with-roasted-tomatoes/