Avocado Veloute Soup

• 3 egg yolks
• 2 garlic (cloves)
• 1 1/2 ripe avocados
• 1 scallions (finely minced)
• 1 lemon
• 1 few drops tabasco chives (finely minced fresh)
• 1,400 ml chicken stock (hot)
• 350 ml cream (heavy)
• 28 gr sweet butter
• 10 gr flour