Add the broth to a sauce pan over low heat. Cover with a lid until you're ready to use it.
Heat 3 tablespoons olive oil over low heat in a large sauté pan. Add the onions and sweat for about 5 five minutes. Then add in the garlic and sweat for 1 minute more.
Next add in the rice, stir to combine it with the oil, onions and garlic and toast for 1 minute. Then add in 1 l cup of the warm broth and bring to a gentle simmer, stirring frequently while allowing the liquid to fully absorb.
For the next 30 minutes continue this process of adding in the broth, 1 cup at a time, bringing it to a gentle simmer, stirring frequently and allowing the the liquid to absorb. The risotto is done when it is soft but still al dente in the middle. You may use all 4 cups of broth, or more or less (see notes).
When the risotto is done cooking taste and season with salt if desired. Add in the peas, stir and cook for 2 minutes. Remove the risotto from the heat and set the pan aside.
Meanwhile heat the remaining 3 tablespoons olive oil in a sauté pan over low heat. Turn the heat up to medium and sauté the radishes until they are bright pink. Then add in the asparagus, lemon juice and pepper. Sauté for 5 minutes or until the asparagus is tender. Taste and season with salt.
Portion the risotto into bowls and top with the spring vegetables. Add more black pepper and a squeeze of lemon if desired.
You can add in more or less broth (it may be more than 4 cups) until you've reached your desired consistency.