The phrase "as I asserted" is correct and usable in written English.
You can use it when you want to refer back to a statement or claim you previously made.
Example: "The results of the study support my earlier conclusions, as I asserted in my previous report."
Alternatives: "as I stated" or "as I claimed".
As I asserted in my last Economix post, I support a preferential rate for manufacturing because of its disproportionate spillover benefits for exports, high-wage job opportunities, investment in research and development and innovation.
Normando was in the audience as I asserted all of that in my lecture, nodding in agreement.
Thus, as I asserted previously, there is no irreducible complexity in eubacterial flagella [ 97]: the most complex macromolecular machine of all in bacteria – creationists, who use it as a spurious argument against evolution [ 98], take note!
To show this we use Łukasiewicz's later parenthesis-free notation (see the supplementary document (Łukasiewicz's Parenthesis-Free or Polish Notation) and his symbols '$\vdash$' for assertion and '$\dashv$' for rejection, to be read respectively as "I assert" and "I reject".
But if the afterlife is, as I assert, an eternal recurrence of this life, then the meek must dine in perpetuity on low carbs and broiled chicken with the skin removed.
To soothe and encourage me by reveling in my awesome experience in Park City as I assert my newly independent self.
Gohmert asked again for a point of personal privilege and said that Holder was "wrong on the things that I asserted as fact".
What if I asserted my will and I was wrong?
In Parliament, as his colleague, I assert that he was a seriously underused talent by the Labour leadership.
The process never ends, I assert as an editor and writer, just as the editing process never ends, as I and so many of my colleagues grapple toward perfection.
Where they promote the new mythology as an antidote for self-absorption, I assert that they are manufacturing a drug that induces it.
