In large saucepan bring vegetable stock just to boiling; reduce heat to a simmer. Fill a large bowl half full with ice water. Plunge fresh basil into simmering stock. Using tongs, immediately transfer basil to ice bath to cool. Remove basil from ice bath, shaking off excess water.
For pesto, in blender or food processor combine basil, the 2 cups spinach, garlic, 1/4 cup of the oil, vinegar, and 1/4 tsp. of the kosher salt. Cover and blend until pesto mixture is smooth.
Add asparagus to simmering stock; cook about 1 minute or until bright green and barely tender. Using a slotted spoon, transfer asparagus to ice bath. Remove from ice bath; set aside. Add artichokes to stock; cook 2 minutes. Using slotted spoon, transfer artichokes to ice bath. Remove and set aside. Add peas to stock; cook 30 seconds. Transfer to ice bath with slotted spoon; drain.
In a 4- to 5-quart Dutch oven or large pot heat the remaining 1/4 cup olive oil over medium heat. Add chopped onion and remaining 1/4 tsp. kosher salt; cook and stir about 5 minutes or until onion is tender. Add rice; cook and stir 2 to 3 minutes or until rice is translucent. Start adding stock to the rice, 1 cup at a time, while continuously stirring with a wooden spoon. As stock is absorbed, add another cup. Continue cooking and adding stock until all of the stock is absorbed and the rice is creamy and tender. (This should take about 20 minutes.) Add zucchini, pesto, and cooked vegetables to the rice the last 2 minutes. Serve topped with fresh spinach leaves and halved cherry tomatoes.