In a large mixer bowl add the brown rice, pinto beans, carrots, celery, onion, red bell pepper, pumpkin seeds, coriander, ¾ teaspoon cumin, Kosher salt, ¼ teaspoon black pepper, and eggs. Mix on medium speed, scraping the bowl often, until the mixture is well mixed (30 to 60 seconds). In a 10-inch non-stick skillet, heat 1 of tablespoon olive oil. Meanwhile, form the burger mixture into small 1/3 cup patties. Place about 4 patties into the skillet and flatten slightly. Cook the patties over medium-high heat until golden brown on the first side (4 to 5 minutes). Turn the patties over and continue cooking until the second side is golden brown (2 to 3 minutes). Remove the patties from the skillet and keep warm. Repeat with the remaining patties, adding 1 additional tablespoon of olive oil to the skillet, if needed. In a small mixing bowl stir together the sour cream, jalapeno, garlic, lemon juice, ¼ teaspoon cumin, and salt. Serve the burgers on top of miniature buns and serve with a dollop of the sour cream sauce. Refrigerate leftovers.