Fry the bacon in a large skillet over medium heat until crispy. Remove from the skillet and place on paper towels to drain any excess fat. Chop the bacon into small pieces and set aside in a small bowl.
In a large bowl, mix together the chopped broccoli and cauliflower. Add the onion, cheese, and bacon and toss into the cauliflower mix.
In a separate bowl combine mayonnaise, sugar, and lemon juice and stir to combine well.
Pour the dressing on top of salad and stir to combine. Refrigerate until ready to serve.