Neither is correct. You need to either say 'find a new recipe', or make it plural and say 'find new recipes'.
That being said, I don't find either one very natural. I'd say "They experiment to find new recipes/a new recipe".
It's a little unusual to use the verb 'experiment' with cooking, but it can work. I have a better verb in mind to express the idea, but I can't think of it at the moment. Maybe after the coffee kicks in I'll comment further.
Edit: I guess the verb I was thinking of was 'improvise'.
Student or Learner