Place in medium saucepan, add enough water to cover, then place on medium heat. Bring to a gentle boil, then cover and cook until fork tender.
While potatoes cook, cut off tips of asparagus spears and set aside. Finely chop remaining stems.
When potatoes are done, remove cover and add asparagus tips to saucepan. Cook one minute, then remove from stove, drain and set aside to cool.
To make pesto, in nonstick skillet, heat olive oil over medium heat. Add garlic, cook one minute or until just golden, then scrape into food processor bowl.
Return skillet to stove and add onion and reserved chopped asparagus stems.
Saute for 4-5 minutes until softened, then add to food processor along with spinach, parsley, walnuts, salt, vinegar. Pulse until finely ground, adding enough water to make a pesto like texture, scraping mixture down as needed.
To serve, toss together cooked potatoes and asparagus spears with the pesto mixture until just combined.
Fold in cheese blend and garnish with plenty of freshly ground pepper and additional chopped parsley.