Heat a skillet over medium heat. Toast pumpkin seeds on skillet until golden brown. You will start to hear the pumpkin seeds pop, don’t worry this is a good thing. Toss seeds frequently in the skillet to prevent burning. Remove and let cool.
Take cilantro and trim off dry ends. Form into a bunch and rip in half. Toss cilantro into food processor, along with toasted pumpkin seeds, garlic, lemon juice, Parmesan cheese, toasted sesame seed oil, olive oil, salt and pepper, and red pepper flakes (optional). Pulse until smooth, periodically scraping down the sides.
To store, keep in an airtight container. Drizzle a bit of olive oil over the top to cover the entire surface to keep the pesto fresh and prevent browning.