How to Make It
If using fresh peas, blanch them in a small pot of boiling water for 5 minutes; drain. In a small skillet, cook the blanched or thawed frozen peas with the spinach and 1/4 cup of the olive oil over high heat until the spinach is wilted, about 2 minutes. Let cool, then transfer to a blender or food processor. Add the lemon juice, goat cheese, Pecorino Romano, mint and lemon zest and puree until smooth. Season with salt and pepper and transfer to a small bowl.
In a blender or food processor, combine the tomatoes with the cucumber, celery and basil and puree until smooth. Strain the mixture through a fine sieve set over a bowl, pressing hard on the solids. Stir in the scallions, garlic, harissa and the remaining 1/4 cup of olive oil. Season with salt and pepper and refrigerate until chilled, at least 30 minutes or overnight.
Ladle the tomato soup into bowls. Drizzle with the sweet pea puree and serve the soup at once.
Harissa, the Tunisian chili paste, is available at Middle Eastern markets and specialty food stores.