Turn Instant Pot on to Saute mode. Add olive oil followed by ground mustard and asafoetida. Saute for a minute, then add in onion and garlic if using.
Otherwise add in dill, sweet potatoes, carrots, and celery. Saute for 2-3 minutes, then add in 1 tbsp olive oil, lemon juice, cashews, white pepper, salt, and water.
Switch Instant Pot to pressure cook, and cook on high pressure x 8 minutes, with natural pressure release.
In the meantime, toss broccoli and the bread (separately) in oil, a pinch of salt, and a pinch of white pepper (optional) and place in a thin later on a parchment paper lined baking sheet. May need two separate baking sheets depending on the size. Bake bread for 10-12 minutes until slightly browned and broccoli for 17-20 minutes until broccoli appears soft and is just beginning to brown.
Place contents of Instant Pot in a high speed blender along with nutritional yeast if using, and 1/2 of the roasted broccoli saving the other half for garnish. Can also use an immersion blender but it doesn’t blend as nicely in my opinion.
Blend to a puree. Pour into serving bowls, garnish with remaining broccoli, drizzle of olive oil, and bread, enjoy hot.