Yes. – Egg White Protein Powder is allowed, in any amount, on the slow carb diet.
Recommended Vegan protein sources are:
Pure Advantage Pea Protein Isolate
Sun Warrior Brown Rice Protein
Nitro Fusion Plant Fusion (Rice, Pea, and Artichoke Protein)
These protein powders can be mixed with Almond Milk, and 1-2 Tablespoons of Almond Butter.