If you're using a pizza oven, fire it up! Of course if you're not, preheat the oven to as hot as it will go - usually around 550. If you are using a pizza stone, which is preferable, preheat this as well. If you don't have a pizza stone you can use a baking sheet, also preheated.
On a well floured surface, stretch and roll your your pizza dough to ¼ inch thick disc around 12 inches in diameter.
Thinly slice your lemon to about ⅛ of an inch thick, using either a mandolin or very carefully with a knife.
Assemble your pizza: Start with a drizzle of olive oil over the dough. Spread ricotta cheese, followed by pesto, blending the two with the spoon as you go. Sprinkle with mozzarella and season with salt. Layer thin slices of lemon over the top.
Using a pizza peel or the back of a cookie sheet, transfer your assembled pizza to the preheated baking surface. If cooking in a pizza oven, the pizza will only take about 90 seconds to 2 minutes to bake. If baking in the regular oven, bake for about 10 minutes, rotating once while baking, until browned and cheese is bubbly.
Top pizza with dollops of fresh pesto and serve.