For the dipping sauce: Put the basil, dill, mint, chives, Roasted Meyer Lemon juice, mayonnaise and Greek yogurt in a food processor and process until smooth. Season to taste with salt. Store in an airtight container in the refrigerator until ready to serve.
For the arancini: Remove 1 cup of the frozen peas and reserve for later use. Put the remaining peas in a blender with 1 cup of the vegetable stock and puree until smooth. Pour the pea mixture into a medium saucepot and add the remaining 3 cups stock and 2 teaspoons salt. Bring to a low simmer over medium-low heat.
Melt 2 tablespoons of the butter in a medium Dutch oven over medium-high heat. Add the rice and cook until opaque and lightly toasted. Stir in the shallot and garlic; cook an additional 2 to 3 minutes to toast the garlic and soften the shallot. Deglaze the pot with the white wine, then bring to a boil and cook until almost completely reduced. Ladle in one-third of the hot stock, lower the heat to medium, and bring the stock to a simmer, stirring often. Continue to stir the rice for 8 minutes while the stock reduces almost completely. When there is more rice in the pot than liquid, add another third of the stock and repeat stirring and reducing the stock for another 8 minutes. Add the remaining stock and this time reduce just until the rice is thick enough that a spoon leaves a momentary trail when dragged along the bottom of the pot. Remove from the heat and stir in the remaining 2 tablespoons butter, Parmesan, lemon zest, reserved peas, and additional salt and black pepper to taste.
Lightly grease a baking sheet with canola oil and spread the risotto in an even layer; set aside to cool. When the risotto is room temperature, cover it with plastic wrap, pressed directly to the surface of the rice, and refrigerate for 4 hours or up to overnight.
Form the chilled risotto into 19 arancini balls, about 1/4 cup each. Flatten each ball with the palm of your hand, place a heaping teaspoon of mozzarella in the center and fold the sides up and around the cheese. Roll back into balls. (At this point, you can hold the arancini overnight on a baking sheet covered with plastic wrap.)
When ready to fry, heat 2 to 3 inches of canola oil to 350 degrees F in a large cast-iron pan. Line a baking sheet with paper towels.
Whisk the eggs together in a shallow dish and season with salt and pepper. In a second shallow dish, add the panko and season with salt and pepper. Dip the arancini in the egg and then coat in the panko.
In batches of a few at a time, fry the arancini, turning, until deep golden-brown and crispy on all sides, about 4 minutes. Remove with a slotted spoon and drain on the paper towels; immediately season with salt.
Serve hot with the dipping sauce.
Roasted Meyer Lemon:
Heat a cast-iron pan over medium-high heat; add the honey and olive oil. When the honey is melted, stir to combine, then place the lemon halves, cut-side down, into the mixture. Cook until the lemons appear charred and the honey has caramelized to the cut surfaces, about 4 minutes. Remove the lemons to a baking sheet and let to cool.
If you do not make the Roasted Meyer Lemon, you can substitute it for 2 tablespoons fresh lemon juice and 1 teaspoon honey.