1. Cook pasta according to package directions. Drain and let cool, or rinse with cold water and drain again. Drizzle with about 1 tbsp. oil to prevent clumping.
2. Meanwhile, whirl almonds and garlic in a food processor until finely chopped. Add lemon zest, sorrel, 1/2 cup oil, and the salt, whirling until just blended but still coarse.
3. Mix room-temperature pasta in a large bowl with pesto and another 1 to 2 tbsp. oil if needed for a looser texture. Transfer to plates, grate cheese on top, and drizzle with oil.
*Find sorrel in most grocery stores, alongside herbs.