Preheat oven to 450°.
Cut 1/2" off top of garlic and drizzle with oil. Wrap in foil and roast until tender, about 45 minutes.
Meanwhile bring a small pot of salted water to a boil. Rinse asparagus, snap off the tough woody bottoms and cut into thirds. Add asparagus and peas to boiling water and cook for 5 minutes. Drain and run under cold water for 30 seconds. Rinse and chop lettuce. Using a mandolin or sharp chef’s knife thinly slice radish. In a salad bowl toss together, asparagus, romaine, radishes, peas and mint.
Unwrap garlic and let cool. Squeeze garlic cloves into a bowl and mash with the back of a fork until you have a smooth paste. Stir in lemon juice, chives and olive oil. Season with salt and pepper. Toss dressing with salad and serve.