For the blueberry sauce: Place the blueberries in a small saucepan. Add 1/2 cup water, then stir in the honey. Heat over medium-high heat until the mixture comes to a low boil and the blueberries just start to break apart. Dissolve the cornstarch in 2 tablespoons cold water in a small bowl, then add the slurry to the saucepan and bring the mixture to a rolling boil. Turn the heat down and simmer on low heat until the sauce is nicely thickened, 2 to 3 minutes. Remove from the heat and stir in the lemon juice. Set aside until ready to serve. (See Cook's Note.)
For the pancakes: Whisk together the flour, sugar, baking powder, baking soda and salt in a large bowl.
Whisk together the ricotta, milk, vanilla, eggs and lemon zest and juice in a separate medium bowl. Add the wet ingredients to the dry ingredients and stir with a wooden spoon until just combined.
Preheat the oven to 175 degrees F.
Heat about a tablespoon each vegetable oil and butter in a large nonstick skillet (I prefer cast-iron) over medium heat. When the butter is foamy, reduce the heat to medium-low and ladle a heaping 1/4 cup pancake batter into the skillet. Repeat to make 2 more pancakes. Cook until bubbles start to form in the batter and the pancakes are golden underneath, about 3 minutes. Flip and cook the other sides until golden, another 3 minutes. Place the finished pancakes on a sheet tray and hold the oven while you finish cooking the remaining batter, adding more oil and butter as necessary. Serve warm with the blueberry sauce.
Blueberry sauce can be made up to 2 days ahead and stored in the refrigerator. Warm over low heat when ready to use. If the sauce is too thick, add water 1 tablespoon at a time until the desired consistency is reached.