Soak pumpkin seeds in hot water for at least 2 hours (or overnight). Drain the seeds well by shaking to remove excess water.
Place the seeds in a food processor or blender and add the remaining ingredients. Blend until a thick, gritty mixture forms, stopping frequently to scrape down the sides.
Taste it and season with more salt or lemon juice, if desired. Serve at room temperature with tortilla chips, radishes, cherry tomatoes and carrots.