Preheat the oven to 425 degrees and line 2 baking sheets with silicon lining or parchment paper. Toss potatoes with 1/2 tsp salt and 1/2 tbsp of olive oil (optional). Spread potatoes on to a baking sheet. In the same bowl, toss the green beans with the other 1/2 tsp of salt and 1/2 tbsp of olive oil (optional). Spread green beans on to the other baking sheet. Roast both trays of veggies for 35-40 minutes, tossing veggies halfway through.
While veggies are roasting, make you tahini sauce. Add all ingredients to a bowl, except for water, and mix to combine. Add water, a little bit at a time, until you get a smooth and creamy consistency. Adjust flavors as needed.
If using this salad for meal prep, in 4 separate 3 cup glass food storage containers, evenly distribute the artichokes, garbanzo beans, lettuce or arugula, sweet potatoes and green beans. Drizzle with simple tahini sauce. Add avocado right before serving and drizzle with lemon juice.