Place the first five ingredients in a blender in the order listed. Pulse and blend until smooth. (May need to stop and stir up from bottom.)
Slowly, through the top of the blender, with the blender running, drizzle in the oil and blend until emulsified.
Stir seeds in by hand. Refrigerate. The mixture will become slightly thicker when chilled. Makes about a cup.
Note: if bottled lemon is used, check to see if it needs to be mixed with water to mimic the strength of an actual lemon; it may be concentrated.