If using sunflower seeds or if not using a high-speed blender, see Notes below for tips on soaking.
Combine the farro, garlic, broth, and water in a large pot. Bring to a boil, then reduce to a simmer. Cook uncovered, stirring occasionally, until most of the liquid is absorbed and the farro is chewy/tender, about 18 minutes.
While the farro is cooking, combine the cheese sauce ingredients in a blender, starting with just 2 tablespoons lemon juice. Blend until completey smooth. Set aside.
Add tomatoes and kale to the pot with the farro. Continue cooking 2 to 3 minutes, stirring occasionally, until wilted and hot. Pour the cheese sauce into the pot, and stir to distribute. Cook for about 5 minutes or until the sauce is bubbling hot and thick. Remove from heat, taste and add more lemon juice and salt, if desired. Serve hot.
Notes
Soaking
Soaking sunflower seeds helps reduce their unique flavor and aroma. So if you're using the seed option, even if using a high-speed blender, I recommend first soaking the seeds in hot water for 30 minutes to 1 hour.If using a standard blender, soak cashews/seeds in hot water for about 1 hour, then drain and rinse. This helps soften them for blending.
Storage
Store leftover farro in an airtight container in the refrigerator for up to 5 days.