Place the jalapeño pepper and garlic in a blender and process until minced.
Add the spinach and arugula leaves, along with the mayonnaise, lemon juice, lemon zest, Dijon mustard, and salt. Blend until smooth.
Once smooth, keep the blender running and slowly add the olive oil and canola oil. Continue to blend until the oils are incorporated into the aioli.
Use immediately, or for best flavor refrigerate for 3 to 6 hours prior to use to allow the flavors (and spiciness) to meld.
Notes
Want it hotter? Try serrano peppers instead of jalapeños. Depending on the size of the serranos (they tend to be smaller), add more to the recipe (but note serrano peppers are often twice - if not more - the heat of jalapeños). Adapted from Earthbown Farm.