Place chopped bacon in your Pressure Cooker and turn heat to medium (Instant Pot: press Sauté button). Stir occasionally and allow the bacon bits to crisp (~4 mins). Remove bacon bits from pressure cooker and place on paper towel to absorb the excess fat.
Sauté onions in bacon fat for roughly 1– 2 minutes until soften. Add in garlic and half of the green onions. Season with a pinch of kosher salt and pepper if you like. Sauté until fragrant.
Deglaze: Pour ~ ⅓ cup (100 ml) chicken stock. Scrub all the brown bits off the bottom of the pot with a wooden spoon. Keep the brown bits as they are very flavorful.
Pressure Cook the Cauliflower Potato Soup: Add 2 bay leaves, cauliflower, and 2 red potatoes in the pressure cooker. Pour the remaining chicken stock into pressure cooker.
Close the lid and cook at High Pressure for 3 minutes. Turn off the heat and use a 10 minutes Natural Release. Open the lid carefully.
Remove Bay Leaves. Blend cauliflower soup into desired consistency with an immersion hand blender. Add 1/2 -1 cup (250 ml) of heavy cream. Taste the soup and season with 2 tablespoons (30 ml) of fish sauce and kosher salt.
Serve: Garnish with green onions, crispy bacon bits, and freshly grated Parmesan cheese. Enjoy immediately. I think you will love it :)