Combine the cannellini beans, lemon juice, tahini, salt, and garlic in the bowl of a food processor or blender and process until very smooth, about 1 minute, scraping down the sides of the bowl as needed.
With the food processor running, slowly drizzle in the olive oil and continue blending until the puree is incredibly smooth, 2 to 3 minutes.
Refrigerate in an airtight container for at least 2 hours before serving.
To serve, smear onto a plate or shallow bowl, pile the giardiniera in the center, and sprinkle with the togarashi.