I bought some empty squeeze bottles for making custom home sauces. An easy starter was Sriracha ketchup. I began with small quantities and used a scale to set my ratios.
4:1(ketchup to Sriracha) was a pretty good blend. You could taste the chilli sauce with every bite, but wasn’t left in flames after eating a few tablespoons of the stuff. Hot heads might want to try a 3:1 or a 2:1 ratio. Only filling the squeeze bottle up a little means you can tweak your mix ratio after sampling.
A pile of Wendy’s fries provided an excellent test medium for my new sauce.