So let each recipe store either a fixed maximum number of rules, or a dynamic number of rules.

And let each rule have a fixed format:

- which element it operates on (cook element, smoke element, pump, vent, fan, ...)
- action (on, off, regulate (temp sensor), pulse, ...)
- start condition (absolute, or relative to start or stop of previous rule)
- start time
- stop time
- regulation parameter (temp sensor value for on and off, or pulse-on, pulse-off time, ...)
- amount value (amount of energy for cooking, if not just pulsed at 100%, rpm for fan if not just pulsed on/off)

Then have the main loop run through all these rules and have in RAM a flag if the rule is active or not, and in RAM keep track of the timer values for pulsed rules.

Some rules will run in sequence. This happens when rule starts based on end condition of a previous rule.
Some rules will run concurrently. This happens when rule starts at absolute time or based on start condition of a previous rule.