Slice chicken breasts thinly, crosswise (about ¼-inch). Whisk together cornstarch, egg white, rice vinegar and 1 teaspoon oil. Add sliced chicken and stir to coat. (I like to use my hands for this.) Place in refrigerator for 20 minutes.
Heat oil in a large deep skillet, over medium heat until hot. Add onion to skillet; sauté 2 minutes, stirring occasionally.
Add the garlic, ginger, lemongrass, curry paste, curry powder, turmeric, sugar and salt and stir to combine. Cook for 1-2 minutes more stirring continuously until nice and fragrant.
Add the chicken broth and bring to a boil. Reduce to a low simmer and cook for 15 minutes, uncovered.
Scoop out the thick coconut cream at the top of the can of coconut milk and add it to the simmering broth. Whisk together cornstarch and remaining liquid coconut milk untill smooth. Add this mixture to broth mixture slowly, while stirring continuously. Continue simmering for 2-3 minutes until sauce has thickened. At this point, you can remove pot from heat and set aside until 15 minutes before serving time (or refrigerate if it will be longer than an hour). Otherwise proceed with next step.
Add chicken, a few slices at a time, distributing evenly into pan. Add shrimp in same fashion. Top with sliced peppers and sugar snap peas.
Return mixture to a medium simmer and cook one minute (don't stir), then cover tightly and turn off heat. Allow to sit for 10 minutes then remove cover. Taste and add more salt and pepper, if needed.
Serve with jasmine rice. Garnish with a light dusting of curry powder and a scatter of the herbs and cashews, if desired.
See Café Tips above for more detailed instructions and tips.