Risotto Primavera

• 3 tomatoes seeded
• 2 potatoes (peeled)
• 1 onion (finely chopped)
• 1 stalk celery
• 1 carrot (peeled)
• 1/2 lemon
• 1,300 ml chicken stock approximately
• 250 gr shelled peas (fresh)
• 180 gr arborio rice
• 130 gr green beans trimmed (fresh)