You generally want some Con. Even though you tank with Dex, you’ll still get hit occasionally, and you don’t want to get laid out flat.
You are getting the 5th level of monk for a bonus attack, but you won’t often be attacking and casting spells in the same turn. And what are you getting out of this build? A tiny increase to elemental damage? You’d do more damage if you focused on just monk or just sorcerer, or a better multiclass combination.
My open hand monk 6 / thief rogue 4 / fighter 2 can have single turns like this:
Attack 1 + sneak attack: 1d6 + 2d6 + 5
Attack 2: 1d6 + 5
Haste attack 1: 1d6 + 5
Haste attack 2: 1d6 + 5
Action surge 1: 1d6 + 5
Action surge 2: 1d6 + 5
Flurry of blows 1: 2d6 + 10
Flurry of blows 2: 2d6 + 10
12d6 + 50
With the ability to stunning strike on normal attacks and push or topple enemies in flurries.
That’s synergy. Focused entirely on one thing, lots of attacks.
Of course, you don’t need to do what’s numerically advantageous. If you’d rather play for flavor, that’s perfectly valid. Your character was actually my first 5E table top character (but a half elf instead of Dragonborn) and it only really worked because I rolled stats and rolled really well. But since you asked, I can tell you from experience, this isn’t a good build.
