Cook pasta in a large pot of boiling salted water until al dente, according to package instructions. Reserve ¾ cup of pasta water.
Heat a large skillet over medium heat, add olive oil and onion, saute until translucent, ~3-4 minutes. Add garlic and saute ~1 minute. Lower heat to low then add cream cheese, yogurt, zest, and lemon juice, whisking and adding pasta water a little at a time to create a sauce with a consistency that you prefer (more water will create a thinner sauce, you may not use all the reserved pasta water) and heat gently. Mix in dill, salt, and pepper.
Take sauce off the heat and stir in capers, salmon, and cooked pasta. Garnish with sesame seeds and poppy seeds.
National Pasta Association Recipe