How can I stabilize Sriracha in sour cream?

I make a spicy Tzatziki inspired sauce to go with certain cuts of lamb, and I've been having some trouble getting the spicy part to be consistent.

I use cucumber (no seeds or peel), sour cream, fresh mint leaves, Sriracha, cinnamon, salt/pepper and garam masala. When I make the sauce, it tastes perfect, and continues to keep consistently for about 30 minutes chilled.

After about 30 minutes, the pungency of the Sriracha starts to disappear in the sour cream, to the point that it's almost undetectable even two hours later (chilled, all the while). I realize this is what milk fats do when they encounter the work of capsicum :)

Is there any way I can slow down that process without altering the flavor of the sauce? I can't make it sweeter, or it would overpower the lamb. I'm just hoping to extend the shelf life of the sauce in the fridge a few days, right now I just add more Sriracha after tasting the leftover sauce cold, which is kind of hit-or-miss.

I've tried using finely chopped bird's eye chilis without seeds / ribs, but it's quite overpowering initially though it mellows out a day or two later. I'd love to not need to make the sauce that far in advance.